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Koky chem > Paper 2 Collection ✓ > Flashcards

Paper 2 Collection ✓ Flashcards

Revise SC1 - 7, 9, 17 - 26

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1
Q

SC1a - What are the arrangements of particles in each of the three states?

A
  • Solid: Regular and close together
  • Liquid: Random and close together
  • Gas: Random and far apart
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2
Q

SC1a - What are the movements of particles in each of the three states?

A
  • Solid: Vibrate around a fixed position
  • Liquid: Move around each other
  • Gas: Fast in all directions
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3
Q

SC1a - What are the names of the two state changes between solid and liquid?

A
  • S→ L is Melting
  • L → S is Freezing
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4
Q

SC1a - What are the names of the two state changes between liquid and gas?

A
  • L→ G Evaporating (and Boiling)
  • G → L Condensing
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5
Q

SC1a - What are the names of the two state changes between Gas and Solid?

A
  • G → S Deposition
  • S → G Sublimation
  • During these processes they do not become liquid
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6
Q

SC1a - What is overcome during melting and boiling?

A

Forces of attraction between particles

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7
Q

SC1a - In a heating curve, at which points will the line be flat?

A

During Melting and Boiling [phase changes] as the temperature doesn’t increase while the forces of attraction are overcome.

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8
Q

SC2a - What are the two key features of a pure substance?

A

The composition:

  • Cannot be changed by physical means
  • Is the same in all parts of a piece of the substance
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9
Q

SC2a - What is a mixture?

A
  • A mixture contains multiple elements/compounds that aren’t chamically joined together.
  • The composition cannot be changed and so it isnt a pure substance.
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10
Q

SC2a - How will the heating curve of a mixture look different to a pure substance and why?

A
  • Instead of straight lines there will be curves.
  • This is because there are multiple different elements which will have different melting points.
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11
Q

SC2b - What is filtration?

A

Using a filter to trap larger insoluble substances from a mixture.

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12
Q

SC2b - What is cystallisation?

A
  • When a solution is evapourated, meaning that the solvent turns to gas leaving behin dthe solute which forms crystals.
  • The size of these crystals depend on the time the crystallisation takes
  • (Longer time taken = larger crystals)
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13
Q

SC2b - What is a saturated solution and how can this be changed?

A
  • A saturated solution is a solution in which a solvent contains the highest amount of dissolved solute as possible.
  • This limit can be increased by increasing the temperature.
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14
Q

SC2b - Descirbe what a risk assesment is and how it is used when crystallising in a lab.

A
  • Identifying and evaluating the hazards and considering ways of reducing the risk of harmful effects.
  • In crystallisation this would be indentifying:
    • The solution can spit: wearing eye protection and removing from the bunsen burner before the solution is completely evapourated
    • You can get burnt from the bunsen burner: keep your hands away from the flames at all times
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15
Q

SC2c - What is paper chromotography?

A
  • A method of speration that involves having a piece of paper with dots of ink slightly dipped in the water (so that the water doesnt reach the pencil line that the ink is one).
  • The solvent is called the mobile phase and the paper contains the stationary phase.
  • If an ink moves less up the page it is less attracted to the stationary phase.
  • Different inks have different levels of attraction to the stationary phase and so will get sperated out at different distances.
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16
Q

SC2c - How do you measure the Rƒ value of an ink?

A

Rƒ = Distance travelled by spot ÷ Total distance travelled by solvent

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17
Q

SC2c - What can paper chromotography be used for?

A
  • Distinguishing between pure/impure substances
  • Identifying substances by comparing their chromotogram with known substances
  • Identifying substances by calculating their Rƒ value
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18
Q

SC2d - What is simple distillation?

A

The separation of a liquid from its dissloved solids, by evapourating it and condensing the gas formed.

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19
Q

SC2d - What conditions do the components of the solution have to meet for simple distillation to work?

A

They have to have boiling points that are at least 25° C apart.

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20
Q

SC2d - Describe a simple distillation set-up.

A
  • A side-arm flask on a tripod over a bunsen burner.
  • It contains the solution and anti-bumping granules to help the liquid boil more smoothly.
  • A thermometer is connected to the top.
  • A delivery tube, leading to a conical flask, is surrounded with a cooling jacket (condenser) which takes cold water in from the bottom and puts it out at the top.
  • The conical flask is in a bath of ice water.
  • The bunsen burner is ona heat resistant mat.
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21
Q

SC2d CP - Which two methods can you use to seperate solvents in an ink?

A
  • Paper chromotography
  • Simple distillation
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22
Q

SC2e - Why can’t water be purified by distillation on a large scale?

A

It takes up too much energy.

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23
Q

SC2e - Why can’t tap water be used for chemical analysis?

A

Tap water contains small amounts of dissolved salts and minerals which may react and alter the resuslts

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24
Q

SC2e - Describe the stages river water goes through before it can be used in homes.

A
  • First, it is screened with a seive to get rid of large objects such as leaves and twigs
  • It is then sent to a sedimentation tank where small particles will settle out at the bottom
  • The water is then filtered through layers of sand and gravel
  • Finally it is treated with chlorine to kill microbes
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25
Q

SC3a - Name the three base rules of atomic theory.

A
  • All matter is made up of atoms
  • Atoms cannot be broken down into smaller parts
  • Atoms cannot be created or destroyed
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26
Q

SC3a - Names the three subatomic particles as well as their relative mass and charge.

A
  • Protons:
    • M: 1
    • C +1
  • Neutron:
    • M: 1
    • C Neutral (0)
  • Electron:
    • M: 1/1835 (negligible)
    • C -1
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27
Q

SC3a - Describe the structure of an atom

A
  • Protons and neutrons centred in a nucleus.
  • Electrons orbiting outside in electron shells.
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28
Q

SC3b - What did the Rutherford Gold foil test reveal about the space inside atoms?

A

Atoms are mostly empty spcae

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29
Q

SC3b - What is an atomic number?

A

The number of protons in an atom. the bottom number on the symbol for an element

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30
Q

SC3b - What is a mass number?

A
  • The number of protons + neutrons in an atom (the mass).
  • The top number on the symbol for an element.
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31
Q

SC3c - What is an isotope?

A

Two atoms (of the same element) with the same atomic number but different mass numbers (amounts of neutrons)

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32
Q

SC3c - What does the symbol Ar stand for and what does it mean?

A
  • Relative Atomic Mass.
  • The average mass of the naturally occurring form(s) of an element in relation to a Carbon-12 atom
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33
Q

SC3c - How do you calculate the Ar of an element from the abundance of its isotopes.

A

(M1 x A1) + (M2 x A2) (etc.) ÷ 100 (M=Mass A=Abundance)

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34
Q

SC3c - Why does chlorine have a mass number with a decimal?

A
  • It is its relative mass.
  • There are two isotopes of chlorine, 35 and 37.
  • Chlorine - 35 is more abundant than 37.
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35
Q

SC4a - How did Medeleev organise his periodic table?

A

By increasing atomic mass

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36
Q

SC4a - What two things did Mendeleev do to the order of elements in his table that made it more sucessful than others?

A
  • Left gaps for certain elements
  • Swapped elements around
  • He did this because he realised a trend in the chemical and physical properties in relation to the groups of elements
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37
Q

SC4a - How did Mendeleev predict the property of elements such as eka-alluminium (now known as gallium)

A

He identified the trend in properties down a group and used this information to estimate the properties of undiscovered elements

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38
Q

SC4b - Why does (in the modern periodic table) Tellerium come before Iodine despite having a greater mass number?

A
  • Iodine exists mostly as Iodine-127
  • Tellerium has many isotopes ranging from Te-126 to Te-130
  • This means Tellerium’s Ar is ~128
  • This proves one reason why it is more reliable to order elements by increasing atomic number than by mass number
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39
Q

SC4b - How is the atomic number related to energy given off in x-rays when electrons are fired at an element?

A
  • The square root of the energy given off is directly proportionate to the atomic number.
  • This realisation proved the idea of protons and that the atomic number is the number of protons in an atom.
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40
Q

SC4b - What are the four main features of the modern periodic table?

A
  • Elements in a period are in order of increasing atomic number
  • Elements with similar properties are in the same group
  • Non-metals are on the right and metals are on the left
  • The Iodine Tellerium pair reversal is explained
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41
Q

SC4c - How do atoms store electrons?

A
  • Atoms have electrons in orbits of electron shells around the nucleus
  • The first shell holds up to 2 electrons
  • The second and third shell holds up to 8 electrons
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42
Q

SC4c - How do you work out the electron configuration of an element? Use Chlorine (Atomic number 17) as an example

A
  • Atomic number 17 means 17 protons and thus 17 electrons. 1
  • 7-2 is 15, 15-8 is 7, 7-8 is a negative number so there are 2 in the first shell,8 in the second and 7 in the third 2.8.7
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43
Q

SC4c - How does the electron configuration of an atom relate to its position on the periodic table in terms of group and period?

A
  • The total amount of electron shells will be the period it is in.
  • The number of electrons in its outermost shell is equal to the group that it’s in.
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44
Q

SC5a - When ionically bonding, what happens to:

  • Metals
  • Non-metals
A
  • Metals loose an electron(s) as they are closer to 0/8 electrons in their outermost shell and so its easier to loose electrons
  • Non-metals are closer to 8/8 electrons in theri outermost shell and so it is easier for them to gain electrons
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45
Q

SC5a - What is the type of attraction in an ionic bond?

A

Electrostatic forces of attraction

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46
Q

SC5b - How do you work out the ionic formula of an atom and a compound?

A
  • An atom’s ionic formula will depend on the numbe rof electrons in its outer shell.
  • If it has to loose electrons to gain a full outer shell, it will be positive by that much.
  • If it has to gain electrons it will be negative by that much.
  • In a compound, the charges of the ionic compound of an element need to cancel out.
  • e.g Mg 2+ and O 2+ will form MgO while Na+ and S2+ will form Na2S
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47
Q

SC5b - What is an ionic lattice structure?

A

When billons of ions are packed together in a regular structure.

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48
Q

SC5b - What are the main 5 polyatomic ions?

A
  • Ammonium, NH4+
  • Hydroxide, OH-
  • Nitrate, NO3-
  • Carbonate, CO32-
  • Sulfate, SO42-
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49
Q

SC5c - Are the melting and boiling points of Ionic compounds high/low and why?

A

They are high as they have strong electrostatic forces of attraction which require a lot of energy to overcome and break

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50
Q

SC5c - Are ionic compounds electrically conductive and why/why not?

A

For a substance to be conductive it must contain particles that are:

  1. Charged
  2. Free to move

So Ionic compounds can conduct electricity when they are aqueous or molten.

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51
Q

SC5a - What is a cation and an anion?

A
  • Cation: A positively charged ion (A metal which has lost an electron) Anion
  • A negatively charged ion (A non-metal which has gained an electron)

CAT-ions are PAWS-ative (Thank you Mr. Moore #gonebutnotforgotten)

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52
Q

SC5c - How does an aqueous ionic compound conduct electricity?

A

The negative ions flow to the anode(+) and the positive ions flow to the cathode(-). electrons do not flow.

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53
Q

SC6a - How do covalent bonds work?

A
  • Two atoms with incomplete outer electron shells, share some electrons so that they each have full shells of electrons.
  • For example Hydrogen is missing one electron and Chlorine is missing one and so they bond and have a pair of electrons shared between them.
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54
Q

SC6a - Why do molecular compounds (covalently bonded) have low melting points?

A

While the electrostatic forces between the atoms in single molecule are very strong, the intermolecular forces of attraction are very weak and so they require little energy to break.

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55
Q

SC6a - What is the valency of an atom and how does this affect the amount of bonds it forms?

A
  • The valency is the number of empty spaces in its outermost shell.
  • The valency is equal to the total number of bonds formed.
  • When Carbon bonds Sulfur there are two sulfurs to one carbon each with a double bond (sharing two pairs of electrons) S=C=S
  • This means each sulfur has a valency of two and the carbon has a valency of four.
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56
Q

SC7a - What is a compound?

A

Atoms of more than one element joined together by chemical (covalent) bonds

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57
Q

SC7a - Why do simple molecular compounds have low m.p/b.p?

A
  • They are formed of covalent bonds
  • While there are strong covalent bonds, the forces between molecules are weak meaning they require little energy to break
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58
Q

SC7a - Why aren’t simple molecular compounds able to conduct electricity?

A
  • For something to be able to conduct electricity it must contain a charged particle that is free to to move.
  • Covalent bonds aren’t based on charges tso it doesn’t meet these requirements
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59
Q

SC7a - What are polymers and monomers?

A
  • Monomers are small simple molecules.
  • When multiple of these join up in a chain, they form a polymer
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60
Q

SC7b - What are allotropes?

A

Different structural forms of the same element

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61
Q

SC7b - Describe the structure and properties of a fullerene?

A
  • Fullerenes are spherical or tubular structures where each carbon atom is bonded to three others
  • They have low m.p/b.p due to weak intermolecular forces
  • They are also soft and slippery
  • Can conduct electricity due to delocalised electron
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62
Q

SC7b - Describe the structure and properties of graphene?

A
  • Flat shape that cna be rolled up
  • Each carbon atom is bonded to threee others meaning there is a delocalised electron allowing conduction of electricity
  • Low m.p/b.p
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63
Q

SC7b - Describe the structure and properties of graphite?

A
  • High melting point due to strong covalent bonds
  • Layers easily slide over eachother due to weak forces between them
  • Three bonds per carbon atom
  • Delocalised electron allows conduction of electricity
  • Useful as a lubricant due to layers sliding
  • Used for electrolysis as it is unreactive and cheap
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64
Q

SC7b - Describe the structure and properties of diamond?

A
  • Tetrahedral structure
  • Four bonds per carbon atom
  • Electrical insulatro due to no free electrons
  • High melting point due to strong covalent bonds
  • Very strong due to tetrahedral structure
  • Used for drills due to strength
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65
Q

SC7b - Whare are diamond and graphite examples of?

A

Giant molecular structures: Huge 3D netwroks of atoms linked by bonds

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66
Q

SC7c - What is metallic bonding?

A
  • Metals are bonded in a giant lattice structure
  • They are held together by the stron electrostatic forces of attraction that exist between the positive metal ions and the negative delocalised electons
  • Strong electrostatic forces of attraction require a lot of energy to break giving them high m.p/b.p
  • Delocalised electron allows it to conduct electricity
  • They are also malleabele
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67
Q

SC7c - How are metals malleable?

A
  • Mallebale means that it can change shape and bend without breaking
  • Metals are a giant lattice structure of positive metal ions delocalised electrons
  • When a force is applied to a metal, the layers slide over each other
  • It doesn’t break because of the ‘sea’ of delocalised electrons holding the metal together by electrostatic forces
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68
Q

SC7c - Why are metals able to conduct electricity?

A
  • To be able to conduct electricity, something must contain a charged particle that is free to move
  • Since metals have a sea of deloclised electrons, it meets these two requirements
  • When a potenital difference is applied, the electrons move to the positive side
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69
Q

SC7c - How does the electrical conductivity of a metal vary?

A
  • As the charge of the ion increases, the number of delocalised electrons per atom increases.
  • This increases the electrical conductivity
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70
Q

SC7d - What are the advantages and disadvantages of using dot and cross diagrams?

A

Pros:

  • Shows how electrons are shared in covalent and ionic bonds

Cons:

  • Do not show the structure formed
  • Suggests that electrons are different
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71
Q

SC7d - What are the advantages and disadvantages of using metallic models?

A

Pros:

  • Shows it is held in a lattice
  • Explains properties such as eletical conductivity

Cons:

  • Doesn’t show the ions to be constantly vibrating
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72
Q

SC7d - What are the advantages and disadvantages of using 3D ball and stick diagrams?

A

Pros:

  • They show the structure that is formed
  • They show the number of bonds per atom

Cons:

  • The atoms are too far apart
  • There aren’t actually any ‘sticks’
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73
Q

SC9a - What is the difference between emirical and molecular forumla?

A
  • Molecular formula is the actual amount of atoms of each element in a compound
  • Empirical formula is the simplest whole number ration of atoms of each element in a compound
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74
Q

SC9a - How do you work out the empirical formul of a compound from the masses of each element?

A
  • Find the moles by doing mass/Mr
  • Divide both of the molar values by the smalles of the two
  • e.g: 10g of Ca and 17.8g of Cl 10/40 = 0.25 17.8/35.5 = 0.5 0.25/0.25 = 1 0.5/0.25 = 2 1:2 ratio
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75
Q

SC9a - Describe how you can find the empirical formula of magnesium oxide by heating magnesium ribbon.

A
  • Place a tripod over a bunsen burner on a heat resistant mat and place a pipeclay triangle on the tripod
  • Sand down the magnesium ribbon and measure its mass
  • Meausre the mass of the crucible and lid
  • Measure the mass of the crucible with the magnesium in and take away your previous result to get the starting value of magnesium
  • Let the magnesium ribbon heat over the bunsen burner in the crucible, lifting the lid occasionally to let in oxygen
  • Weight the mass of the crucible with the magnesium oxide and take away the mass of the crucible to find the mass of magnesium oxide
  • Take away the mass of magnesium to find the mass of oxygne that reacted
  • Use the emirical formula method to use these amsses to sork out empirical formula of MgO
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76
Q

SC9c - What is the molar mass formula?

A

mol = mass/Mr or Ar (relative atomic or formula mass)

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77
Q

SC9b - how do you work out the concentration of a solution?

A

Concentration (g dm-³) = mass of solute (g) ÷ volume of solution (dm³)

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78
Q

SC9b - What is a dm³ equal to?

A

1L = 1000 cm³

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79
Q

SC9b - What is the conservation of mass and what doe sit depend on?

A
  • The idea that the mass of the reactants = the mass of the products in a closed system.
  • In an open system, gases and liquids can sometimes ascape altering this
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80
Q

SC9b - How do you calculate the mass of a reactant needed to make a product (or vice versa)

A
  • Work out the mols in the one you’ve been given the mass for and divide this by the big number next to it
  • Multiply this my the big number next to the one you are trying to work out to give you the mols in this
  • Multiply this by its Mr to get the mass
  • Example: 2Al + 3Cl₂ → 2AlCl3
  • How many grams of Cl₂ to form 53.4g of AlCl3
  • AlCl3 has an Mr of 133.5 so do 53.4 ÷ 133.5 = 0.4
  • As the ratio of big number is 3:2 do 0.4 ÷ 2 and then x 3 to get 0.6 Do 0.6 x Cl₂s Ar whcih is 71 to get 42.6g
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81
Q

SC9c - What is avrogodos constant?

A

The amount of particles in a mole 6.02x1023

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82
Q

SC9c - What iis a limiting reactant?

A
  • When you have the mass of two reactants, one is likely to be in excess meaning that once one is used up the one in excess will stiil have some remaining.
  • As once one has been used up the reaction can’t continue, the one that gets used up first is the limiting reactant
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83
Q

SC9c - How do you work out the limiting reactant?

A
  • Firstly work out the balanced equation of the reaction (This may already be given to you)
  • The big numbers show the rati of mols needed
  • Using the mass and Mr, work out the mols you have of one of them
  • From here, work out the mols you need for the other one for the second one to not be the limiting reactant
  • Then work out how many mols you have of the second one.
  • If it is more than you would’ve needed then it is in excess if not then it is the limitjng reactant
  • Use the values for the actual amount of mols used up to figure out the masses that will actually be used up
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84
Q

SC9c - What is stochiometry?

A

The ratio of moles is a reaction

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85
Q

SC17a - What are the physical properties of the alkali metals (group 1)

A
  • Malleable
  • Good conductors of electricity
  • Relatively low melting points
  • Soft/easily cut
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86
Q

SC17a - Why are alkali metals stored in oil?

A

They are incredibly reactive and would react with the oxygen and moisture in air otherwise.

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87
Q

SC17a - When you cut an alkali metal, a layer of tarnish forms. What is this called and what is the equation for this?

A

This is oxidation.

4x(s) + O2(g) -> 2x2O(s) Metal + Oxygen → Metal Oxide

[Where x is any alkali metal]

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88
Q

SC17a - How does the melting point of the alkali metals change as you go down?

A

It decreases

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89
Q

SC17a - What is the equation for the reaction that takes place when an alkai metal reacts with water?

A

2x(s) + 2H2O(l) → 2xOH(aq) + H2(g)

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90
Q

SC17a - What would you observe when you put lithium, sodium and potassium in water that contains universal indicator?

A
  • Li: Bubbling fiercely on the surface and moves around a bit. Water turns purple
  • Na: Moderate effervesance (fizzing) on the surface. Moves about quicker. Might have a yellow spark. Water turns purple
  • K: Lots of effervesance (fizzing) on the surface. Moves about very fast. Lilac flame produced. Water turns purple.
  • Effervesance/bubbling indicates the presence of a gas (hydrogen)
  • Water turns purple becuase it is alkali.
  • Increased speed indicates a higher rate of reaction
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91
Q

SC17a - What happens to the reactivity of alkali metals as you go down?

A

It increases.

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92
Q

SC17a - The reactivity of alkali metals increases as you go down the table. Explain why this is using Lithium and Potassium as examples.

A
  • Both Lithium and Potassium want to loose their only outer shell electron to gain a full outer shell and become stable
  • Potassium has more shells of electrons and so there are more shells between its positive nucleus and its outer most electron
  • The shells in between shield the positive charge
  • Additionally it is urther away from the nucleus
  • The positive charge from Lithium’s outermost electron is shielded by less shells and so the electrostatic forces of attraction to its outer shell electron are stronger
  • As Potassium has weaker electrostatic forces of attraction to its outer shell electron, this electron can be los tmore easily
  • This means Potassium will be more willing to loose its electron to form an ion making it more reactive.
  • Thus as you go down the group, every extra layer of electron shells makes the element more reactive
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93
Q

SC17b - What is the name for group 7 elements and what is key about their natural state?

A
  • The halogens.
  • They exist covalently bonded as diatomic atoms.
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94
Q

SC17b - What is fromed when a halogen reacts with a metal (e.g. Chlorine and Magnesium)?

A
  • It forms a halide salt.
  • Cl2(g) + Mg(s) → MgCl2(s)
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95
Q

SC17b - What happens to the name of a halogen once it it becomes an ion?

A
  • It changes from -ine to -ide
  • e.g. BromiNe atom to BromiDe ion
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96
Q

SC17b - What is the trend in mp/bp and density of halogens as you go down the group?

A

It increases.

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97
Q

SC17b - What are the appearances of Chlorine, Bromine and Iodine at room temperature?

A
  • Cl: Green gas
  • Br: Brown liquid
  • I:Purple/grey solid
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98
Q

SC17b - What are the properties of Halogen gases?

A
  • Non-metals
  • Diatomic
  • Toxic
  • Corrosive
  • Brittle when solid
  • Low mp/bp
  • Poor conductors of electricity and heat
  • Coloured vapours
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99
Q

SC17b - What is the common use for all the halogens?

A

As disinfectancs/bleaches as they can kill microorganisms and remove stains.

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100
Q

SC17b - Using Hydrogen and Chlorine as examples explain how halogen gases cna be used to from acidic solutions.

A
  • Hydrogen and a halogen bond to from hydrogen halide.
  • This is dissolved in water to from an acidic solution. For example:
  • Hydrogen + Chlorine → Hydrogen Chloride
  • This can dissolved in water to form Hydrochloric acid
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101
Q

SC17b - What is the test for chlorine?

A

Damp blue litmus paper will turn red and bleach white in the presence of chlorine gas.

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102
Q

SC17c - What observations will you make when you heat halogens with iron wool and what does this tell you about the reactivity trend?

A
  • Fluorine: Bursts into flames
  • Chlorine: Glows brightly
  • Bromine: Glows dull red Iodine
  • Changes colour
  • As the reaction gets less violent as you go down the group you can tell that they get less reactive.
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103
Q

SC17c - What is a displacement reaction?

A

A reaction in which a more reactive element displaces a less reactive metal from a compound producing the less reactive metal

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104
Q

SC17c - State what observation you would make in each of these reactions signifying that displacement has taken place:

  1. Fluorine + Potassium chloride
  2. Chlorine + Potassium bromide
  3. Bromine + Potassium iodide
A
  1. Solution turns yellow showing that chlorine has been produced
  2. Solution turns orangey-brown showing that bromine has been produced
  3. Solution turns dark brown showing that iodine has been produced
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105
Q

SC17c - Why is displacement a redox reaction?

A
  • Because both oxidation and reduction occur at the same time.
  • e.g 2Cl- + F2 → Cl2 + F-
  • The chlorine looses electrons at the same time that the fluorine gains electrons and so it is a redox reaction
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106
Q

SC17c - Using Fluorine and Iodine as examples explain why the reactivity of halogens decreases as you go down the group?

A
  • Both Fluorine and Iodine want to gain one outer shell electron to have a full outer shell and become stable
  • Iodine has more shells of electrons and so there are more shells between its positive nucleus and its outer most electron
  • The shells in between shield the positive charge
  • Additionally it is further away from the nucleus
  • The positive charge from Fluorine’s outermost electron is shielded by less shells and so the electrostatic forces of attraction to its outer shell electron are stronger
  • As Fluorine has stronger electrostatic forces of attraction to its outer shell electron, the last needed electron is attracted more easily
  • This means Fluorine will be more willing to gain an electron to form an ion making it more reactive.
  • Thus as you go down the group, every extra layer of electron shells makes the element less reactive as there is more shielding and it’s harder to gain an electron
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107
Q

SC17d - What is another name for the group 0 elements?

A

Group 8 / Noble gases

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108
Q

SC17d - What are the properties of the noble gases?

A
  • Colourless
  • Have very low m.p/b.p
  • Poor conductros of heat and electricity
  • Inert/unreactive
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109
Q

SC17d - What is the trend in m.p/b.p and density as you go down the group?

A

It increases

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110
Q

SC17d - Why weren’t the noble gases discovered until the late 19th century?

A

They don’t form compounds and are in very small amounts in our atmosphere and so are hard to detect.

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111
Q

SC17d - What are the uses for each of the noble gases from helium to krypton?

A
  • He: Used for weather ballons/airships as it is non-flammable and has a low density
  • Ne: Used in electrical signs for its orange-red glow when electricity passes through
  • Ar: Used in the space above wine to preserve it as its denser than air will stop the wine from reacting
  • Kr: Used in photography lighting for its brilliant white light when electricity passes through
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112
Q

SC17d - Describe, in terms of their electron configuration, why halogen gases are inert?

A
  • Halogen gases have complete outer shells (e.g. 2 in helium or 8 in neon).
  • This means that they are stable as their energy levels are full.
  • Thus they ahve no need to loose any electrons.
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113
Q

SC17d - Explain why, despite being a halogen gas, Xenon can still form compounds?

A
  • Xenon has many shells of electrons.
  • These shield the positive charge form the nucleus meaning that the positive electrostatic force of attraction acting on its outer layer is weaker.
  • Thus if it is near to an atom with few shells (such as fluorine) and is close to the positive charge from that nucleus, the elctron may transfer over.
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114
Q

SC18a - What is the rate of a reaction?

A

The speed at which reactants turn into products

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115
Q

SC18a - How can you use a gas syringe to investigate the rate of reaction?

A
  • Works for reactions where a gas is produced
  • Set up a liquid in a conical flask
  • Push a gas syringe to 0 and attach it to a bung
  • Add the granules of the other chemical into the conical flask and immediately attach the bung
  • Also set off a timer. Every 10 seconds record down the value red on your gas syringe
  • Repeat and take the average of concordant results
  • use the average results and plot them on a graph
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116
Q

SC18a - Describe a reactant/product time graph showing the rate of reaction

A
  • Concentration on y axis time on the x axis
  • Products start at 0 and have an increasing positive curve
  • Reactants start high and have an increasing positive curve till 0
  • Both curves will plateau (flatten out) at the same point
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117
Q

SC18a - How can you measure mass to investigate the rate of reaction?

A
  • Work for reactions where one of the products are gases
  • Place the conical flask on the balance at set it to 0
  • Add the liquid being used into the conical flask and then add the other chemical
  • Quickly record down the starting mass and cover the flask with cotton wool to stop acid form spitting
  • Set off timer and record down the mass every 10 seconds
  • Repeat and take the average of concordant results
  • Plot a graph using the average results
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118
Q

SC18b - What are the five main factors that affect rates of reaction?

A
  • Temperature
  • Pressure
  • Concentration
  • Surface areas/volume ratio
  • Presence of a catalyst
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119
Q

SC18b - How does temperature affect the rate of reaction?

A
  • An increase in temperature gives the reactant particles more kinetic energy meaning they move around more
  • This means there will be more frequent successful collisions and more particles will have the required level of energy to react
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120
Q

SC18b - What is activation energy?

A

The minimum amount of energy required for a reaction to occur

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121
Q

SC18b - How does concentration affect the rate of reaction?

A
  • An increase in concentration means more particles in a fixed volume
  • This means that that successful collisions will be more frequent as particles are closer together
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122
Q

SC18b - How does pressure affect the rate of reaction?

A
  • An increase in pressure means the same amount of particles in a smaller volume
  • This means that that successful collisions will be more frequent as particles are closer together
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123
Q

SC18b - How does surface area/volume ratio affect the rate of reaction?

A
  • An increase of the surface area to volume ration means for a fixed volume, there is more surface area.
  • This leaves more of the surface exposed
  • This means that collisions have more surface to occur on and so successful ones occur more often
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124
Q

SC18b - How does the presence of a catalyst affect the rate of reaction?

A
  • A catalyst increases the rate of reaction without being used up by lowering the activation energy required
  • This means more particles will have the required activation energy and collisions will more frequently be successful
125
Q

SC18b CP - Describe how you would investigate the affect of a change of surface on rates of reaction. [Use an upturned measuring cylinder and marble chips with hydrochloric acid]

A
  • Set up the apparatus with a clamp holding an upturned measuring cylinder over a trough containing water
  • Have a delivery tube attached to a bung lead up to the cylinder and record the starting value
  • Put 40cm³ of hydrochloric acid (Use the same concentration throughout) into a flask.
  • Measure out 5g of small marble chips
  • Add the marble chips to the flask and immediately close it with the bung
  • Start the timer and record the value of gas produced every 30 seconds until the reaction has finished
  • Repeat 3 times and take the average of concordant results. Use this to plot a graph
  • Repeat all steps but using large marble chips of the same mass and plot these results on a graph
126
Q

SC18b CP - Describe how you would investigate the effect temperature has on the rate of reaction [Use the disappearing cross method and sodium thiosulfate with hydrochloric acid]

A
  • Measure out 50cm³ of sodium thiosulfate into a conical flask
  • Measure out 5cm³ of hydrochloric acid into a test tube
  • Place the conical flask and test tube in a water bath of a set temperature
  • After the chemicals have acclimatized (around 5 minutes), take them out and add the hydrochloric acid into the flask
  • Place it on a piece of white paper and immediately start the timer
  • Stop the timer once it has turned cloudy and the cross is no longer visible
  • Repeat with different temperatures of the water bath and plot a graph
127
Q

SC18c - What is a catalyst?

A

Catalysts increase the rate of reaction without being used up

128
Q

SC18c - How do catalysts work?

A
  • Catalysts provide an alternate reaction pathway by which a lower level of activation energy is required.
  • This means that more particles will be able to reach the required activation energy and therefore successful collisions will be more frequent
129
Q

SC18c - How will the shape of a reaction profile change when a catalyst is used?

A

The peak will be a lot lower however it will being to rise and stop falling at the same places

130
Q

SC18c - Why are catalysts desirable in industry?

A
  • By increasing the rate of reaction, there will be more products produced in a fixed amount of time.
  • Also, as catalysts don’t get used up, they can be used multiple times.
  • This means that the process is more profitable
131
Q

SC18c - How does a catalytic converter work?

A
  • Combustion inside a car produces toxic gases
  • A catalytic converter uses catalysts of palladium and platinum to convert theses into less harmful gases
  • The catalysts are spread over a thin honeycomb structure because:
    • Increased surface increases the efficiency of the cat con.
    • As little catalyst as possible is used as the metals are very expensive
132
Q

SC18c - What are enzymes and how do they work?

A
  • Enzymes are large protein molecules that act as biological catalysts
  • They have specifically shaped active sites to the shape of their reactant molecules (substrates)
  • Changes in temperature can denature the active site, changing its shape
  • They are used in man things e.g. production of alcohol

You should know this in more detail for biology anyway but yeah….

133
Q

SC19a - What are exothermic and endothermic reactions?

A
  • Exothermic reactions:
    • Energy from stores in bonds is transferred to surroundings
    • Measured temperature will be hotter
    • Products will have less energy
  • Exothermic reactions:
    • Energy is taken in from surroundings is transferred to stores in bonds
    • Measured temperature will be cooler
    • Products will have more energy
134
Q

SC19a - Describe the shape of a simple reaction profile in exothermic and endothermic reactions

A
  • Exo:
    • Horizontal line for reactants
    • vertical arrow down
    • lower horizontal line for products
  • Endo:
    • Horizontal line for reactants
    • vertical arrow up
    • higher horizontal line for products
135
Q

SC19a - Which two types of reactions are always exothermic?

A
  • Neutralisation: Acid + base
  • Displacement: More reactive element displaces a less reactive element that was part of a compound
136
Q

SC19a - Which two types of reactions can be endothermic or exothermic?

A
  • Precipitation: Two soluble reactants form a soluble product #Dissolving: When you dissolve something <strong>#helpful</strong>
137
Q

SC19a - How can you check if a reaction is exo/endothermic using a polystyrene cup and a thermometer?

A
  • Place one of your chemicals in the polystyrene cup (in a beaker for support) and measure the starting temperature.
  • Add the other chemical and then place the lid and push the thermometer through the top.
  • Record the final temperature once the reaction has stopped.
  • Lid used to limit heat loss and polystyrene is a poor conductor of heat
  • A reduction of heat means it is endothermic while an increase of heat means it is exothermic
138
Q

SC19b - In terms of bonds broken/formed, describe how a reaction may be endothermic or exothermic

A
  • When bonds break, energy is released and transferred to surroundings (This happens to the reactants)
  • When bonds are formed, energy is taken in from surroundings (This happens to form products)
  • The energy released into the system (from bond breaking) - the energy used taken out of the system (to form bonds) = the total energy change
  • If the energy change is positive, the reaction is endothermic but if the energy change is negative, the reaction is exothermic
139
Q

SC19b - What is the bond energy of a covalent bond?

A
  • The amount of energy required to break the covalent bonds in one mole (Measured in kJ/mol)
  • It is also the amount of energy required to form one mole of that covalent bond
140
Q

SC19b - How would you label activation energy and overall energy change on a reaction profile?

A
  • Overall energy change is an arrow showing the vertical height change between reactants and products
  • Activation energy is the vertical arrow showing the difference in height between reactants and the top of the ‘hump’
141
Q

SC20a - What is a hydrocarbon?

A

A compound containing only hydrogen and carbon atoms

142
Q

SC20a - What are crude oil and natural gas?

A
  • Natural resources that can be useful (Crude oil needs to be distilled first)
  • They are both finite resources as they are being created much lower than we are using them.
  • Fossil fuels are also non-renewable
143
Q

SC20a - How are crude oil and natural gas formed?

A
  • Layers of dead plants and animals form on a sea bed
  • Layers of sedimentary rock form on top and the organisms are trapped
  • After MILLIONS of years, and the absence of oxygen, crude oil/natural gas can be formed
144
Q

SC20a - Why is crude oil considered a mixture?

A

It contains different types of hydrocarbons (Different lengths and different amount of carbon atoms) and these different hydrocarbons aren’t chemically bonded

145
Q

SC20a - What are petrochemicals?

A

Substances formed from crude oil

146
Q

SC20a - What is the main gas in natural gas?

A

Methane (CH4)

147
Q

SC20b - How is crude oil separated?

A

Using fractional distillation

148
Q

SC20b - What occurs in fractional distillation (of crude oil)?

A
  • Crude oil is heated strongly till it evapourates and the hot vapours are pumped into a fractionating column
  • The fractionating column is hottest at the bottom and coldest at the top
  • As vapours rise, they will cool down and will condense when they reach the fraction at a temperature lower than their boiling point
  • Liquid from each fraction falls into a tray and is pumped away
  • The vapours with the lowest boiling points don’t condense and leave as a mixture of gases
  • Bitumen has the highest boiling point and leaves the bottom as a hot liquid
149
Q

SC20b - What are the products of each fraction (in a crude oil fractionating column), and their uses?

A

Top to bottom:

  • Gases: domestic heating/cooking
  • Petrol: fuel for cars
  • Kerosene: fuel for aircrafts
  • Diesel oil: fuel for cars/trains
  • Fuel oil: fuel for ships
  • Bitumen: surfacing roads and roofs

Greek People Kiss Dutch Fish Babies

150
Q

SC20b - How does the number of carbon atoms (size) change from top to bottom of fractions (Gases to bitumen)

A

It increases from top to bottom(Gases is smallest, bitumen is longest)

151
Q

SC20b - How does boiling point change from top to bottom of fractions (Gases to bitumen)

A

It increases from top to bottom(Gases is lowest, bitumen is highest)

152
Q

SC20b - How does ease of ignition change from top to bottom of fractions (Gases to bitumen)

A

It decreases from top to bottom(Gases is easiest, bitumen is hardest)

153
Q

SC20b - How does visocsity change from top to bottom of fractions (Gases to bitumen)

A

It increases from top to bottom (Gases is lowest, bitumen is highest)

Viscosity is ‘how thick’ the fluid is. high viscosity (bitumen) flows with more difficulty than low viscosity (gases)

154
Q

SC20c - What are the first four alkanes?

A
  • Methane (CH4)
  • Ethane (C2H6)
  • Propane (C3H8)
  • Butane (C4H10)
155
Q

SC20c - What are alkanes?

A

Hydrocarbons with only single covalent bonds between carbon atoms

156
Q

SC20c - What are the compounds of crude oil, mostly?

A

Alkanes

157
Q

SC20c - What does the family of alkanes form and what are the features of this?

A

The alkane homologous series has the features:

  • Molecular formula differs by CH2
  • Formula of CnH2n+2
  • Gradual variation in physical properties
  • Similar chemical properties
158
Q

SC20c - What does the structural formula of alkanes look like?

A

*Just a pic*

159
Q

SC20c - How does the boiling point of alkanes change a they get longer?

A

The boiling points increase. The longer they get, the less the difference in boiling point

160
Q

SC20c - How do alkanes react with oxygen?

A

Combustion: Alkane + Oxygen → Carbon dioxide + Water (With excess oxygen)

161
Q

SC20d - What is combustion?

A

When a hydrocarbon burns and oxidises with the oxygen in the air

162
Q

SC20d - What is complete combustion?

A
  • When a hydrocarbon burns in excess oxygen to produce only carbon dioxide and water (as well as energy).
  • This can be considered oxidation of the hydrocarbon
163
Q

SC20d - What is incomplete combustion?

A

When a hydrocarbon burns in a limited supply of oxygen producing carbon and/or carbon monoxide as well as carbon dioxide and water. energy is also produced (although this is less than complete combustion)

164
Q

SC20d - What is the test for carbon dioxide?

A

Lime water will turn milky in the presence of carbon dioxide

165
Q

SC20d - What are the problems with complete combustion?

A
  • Carbon dioxide can dissolve in atmospheric water to produce dilute carbonic acid (H2CO3) which can cause weak acid rain
  • Rising levels of carbon dioxide in the atmosphere leads to global warming
166
Q

SC20d - What are the problems with incomplete combustion?

A
  • Carbon is black soot or smoke which can block pipes carrying away waste products and can blacked buildings and cause breathing problems
  • Carbon monoxide is an odourless, colourless, toxic gas that binds to the haemoglobin of red blood cells reducing the amount of oxygen that can bind causing sleepiness and unconsciousness and sometimes even death
167
Q

SC20e - Describe how combustion of hydrocarbons can lead to acid rain

A
  • Hydrocarbons contain impurities of sulfur that will oxidise with oxygen creating sulfur dioxide
  • Sulfur dioxide dissolves in water to form sulfurous acid:
    • SO2 + H2O → H2SO3
  • Sulfurous acid can be oxidised forming sulfuric acid:
    • 2H2SO3 + O2 → 2H2SO4
  • Sulfurous acid and sulfuric acid can fall as acid rain
168
Q

SC20e - How can ‘internal combustion’ lead to acid rain?

A
  • Internal combustion engines in cars reach temperatures high enough that air inside the engine can cause the nitrogen to be oxide
  • This forms NOx (x number of oxygen) which is an atmospheric pollutant
  • Nitrogen oxides dissolve with atmospheric water and form nitric acid:
    • NOx + H2O → HNO3 (unbalanced)
  • Nitric acid can fall as acid rain
  • Catalytic converters tend to reduce the NOx produced
169
Q

SC20e - What pH is acid rain?

A
  • <5.2
  • (you may not actually need to know this??? but….)
  • (Also now that I’ve said you may not need to know this i can guarantee you will remember it )
170
Q

SC20e - What are the effects of acid rain?

A
  • Crops don’t grow well in low pHs and so will die
  • Changes conditions required for animals/plants to live in
  • Excess acidity in rivers and lakes can kill fish/insects and prevent eggs from hatching
  • Increased rate of metal’s corrosion:
    • Metal + sulfuric acid → metal sulfate + hydrogen
  • Weathering of limestone (calcium carbonate) buildings due to neutralisation:
    • Limestone + Sulfuric acid → Calcium sulfate + water + carbon dioxide
  • Nitrogen dioxide is a red-brown toxic gas that causes respiratory problems such as bronchitis
171
Q

SC20f - What is the process of breaking down a hydrocarbon and how does it occur?

A
  • Cracking is the process of breaking down a large hydrocarbon (often an alkane) into smaller more useful hydrocarbons (often alkane and alkene)
  • Crude oils are heated to evapourate and the vapours are passed over a catalyst and heated to 〰️650 C
172
Q

SC20f - What are alkenes?

A
  • Alkenes are a type of hydrocarbon
  • Their general formula is CnH2n
173
Q

SC20f - Why are alkanes/kenes saturated/unsaturated?

A
  • Alkanes are saturated as they ONLY contain single (C-C) bonds between carbon atoms
  • Alkenes are unsaturated as they contain ONE double (C=C) bond between their carbon atoms
174
Q

SC20f - How does supply and demand vary between fractions of crude oil?

A
  • While fuel oil and bitumen are in much higher supply than demand, the other are in much higher demand than supply
  • As fuel and bitumen are the two largest hydrocarbons in the fraction, this is the reason for cracking to occur
175
Q

SC20f - What are alkenes from crude oil used for?

A

Creating polymers

176
Q

SC20f - What are the pros and cons of using hydrogen rather than hydrocarbons as fuel for cars?

A

Pros:

  • Naturally is a by product of cracking and can be easily obtained by reacting methane with steam
  • Produces water but no carbon dioxide (no greenhouse gas emissions)

Cons:

  • Hydrogen is a gas at room temperature making it hard to store/transport unless kept at high pressure/liquified
177
Q

SC21a - What was the likely composition of the earth’s early atmosphere?

A

Mainly carbon dioxide with small amounts of water vapour with little to no oxygen

178
Q

SC21a - What was likely responsible for the composition of the earth’s early atmosphere?

A
  • There was lots of volcanic activity in the earth’s early years and so volcanoes probably were a a major part of it
  • They release large amounts of carbon dioxide and water vapour and small amounts of other gases (inc. nitrogen)
179
Q

SC21a - What evidence supports ideas about earth’s early atmosphere?

A
  • Other planets near to earth (i.e. Venus and Mars) are mainly made of carbon dioxide that is thought to be released form volcanoes
  • These planets should have a similar atmosphere to what earth was like before humans affected it
180
Q

SC21a - Why may some scientists think earth’s atmosphere was made up of nitrogen mainly and why was this disregarded?

A
  • Titan, a moon of Saturn is made of of >98% nitrogen
  • However, unlike any other planets closer to earth, titan has an icy interior so is less likely to be similar to earth
181
Q

SC21a - How were the oceans formed?

A

The earth cooled down and the water vapour condensed forming oceans

182
Q

SC21a - What evidence supports the claim that the early atmosphere contained little to no oxygen?

A
  • Volcanoes don’t produce oxygen
  • Iron pyrite can’t form in the presence of oxygen and it can be found in very ancient rocks
183
Q

SC21a - How long ago did oxygen levels start to rise and how do we know this?

A
  • About 2.4 billion years ago, iron oxide started to form. Oxygen had to be present for oxidation to occur
  • There is fossil evidence of microorganisms that produced this
  • Some geologists believe that only after enough oxygen was present to oxidise iron could atmospheric oxygen rise
184
Q

SC21b - Describe the changes in levels of oxygen and carbon dioxide in the earth’s atmosphere

A

Oxygen levels increased and carbon dioxide level decreased

185
Q

SC21b - In what three ways did oceans change the atmospheric composition?

A
  • Water vapour lessened as it formed oceans
  • Carbon dioxide dissolved in oceans reducing carbon dioxide in the atmosphere
  • Sea creatures used the dissolved carbon dioxide to form shells made of calcium carbonate (limestone) allowing more carbon dioxide to dissolve
186
Q

SC21b - How did photosynthesis affect atmospheric composition?

A

Photosynthesis:

Carbon dioxide + Water -> Oxygen + Glucose

This reduced levels of carbon dioxide and increased levels of oxygen

187
Q

SC21b - How are stromalites formed and how does this show oxygen being produced?

A
  • Cyanobacteria are photosynthetic organisms that produce a sticky mucus
  • The mucus traps sand and the organisms need to move above it
  • Eventually, these form stromalites
  • As stromalites have been around for around 3 billion years this suggests that photosynthesis has been occurring for this long
  • Oxygen has been produced by these organisms since then
188
Q

SC21b - What caused a second jump in the levels of atmospheric oxygen?

A

Cyanobacteria evolved forming land plants which photosynthesised increasing the levels of oxygen

189
Q

SC21b - What % of the atmosphere is oxygen?

A

21%

190
Q

SC21b - What is the test for oxygen?

A

In the presence of oxygen, a glowing splint will relight

191
Q

SC21c - Describe the greenhouse effect

A
  • Energy from the sun is transferred to the earth by (shorter) infrared and light waves
  • The earth absorbs some of this, warming up and then emits (longer) infrared waves
  • Greenhouse gases in the atmosphere absorb the energy and re-emit it back to the earth
  • This causes the temperature of the earth’s atmosphere to increase and is called the greenhouse effect
192
Q

SC21c - What are some greehouse gases?

A
  • Carbon dioxide
  • Methane
  • Water Vapour
193
Q

SC21c - Why are greenhouse gases neccesary for our survivial?

A

Without them, the temperature of the earth would avergaely be -18 degrees which is too cold (Considering that it is an average meaning that some will be higher and so some have to be lower)

T̶b̶h̶ ̶I̶ ̶l̶i̶k̶e̶ ̶t̶h̶e̶ ̶c̶o̶l̶d̶ ̶m̶o̶r̶e̶ ̶t̶h̶a̶n̶ ̶t̶h̶e̶ ̶h̶e̶a̶t̶ ̶b̶u̶t̶ ̶I̶ ̶g̶u̶e̶s̶s̶ ̶C̶a̶n̶a̶d̶a̶ ̶w̶o̶u̶l̶d̶ ̶d̶i̶e̶ ̶a̶n̶d̶ ̶p̶r̶o̶b̶a̶b̶l̶y̶ ̶a̶p̶o̶l̶o̶g̶i̶s̶e̶ ̶f̶o̶r̶ ̶i̶t̶

194
Q

SC21c - What is/are the negative effects of the greenhouse effect?

A

It is believed that greenhosue gases leads to global warming and climate change causing avergae weather temperatures around the world to increase too much

195
Q

SC21c - What evidence may we have that greenhouse gases are responsible for global warming?

A

Since ~1850, the burning of fossil fuels (releasing carbon dioxide) for industry and so this inreased CO2 levels. As this has increased, so has average global temperature and this suggests a strong correlation

196
Q

SC21c - What is a casual link and how must scientists show that it exists?

A

When one thing causes another. Scientists must collect evidence of why and how the correlation occurs.

197
Q

SC21c - How may scientists prove that CO2 causes temperatures to rise?

A
  • In a lab, they can prove that CO2 absorbs infrared radiation.
  • Satellite data can also show that with an increase in CO2, there is a decreasing amount of infrared radiation that leaves the earth’s atmosphere.
  • This suggests that CO2 levels cause temperature to rise (Causal link present)
198
Q

SC21d - How has human activity increased global warming?

A
  • Burning fossil fuels releases CO2 which is a greenhouse gas
  • Methane is a much more powerful greenhouse gas and is released when natural gas and oil are extracted
  • Cattle have bacteria that produces methane during livestock farming
  • Soil bacteria in landfill sites and paddy fields produces methane
199
Q

SC21d - What are the effects of climate change?

A
  • Higher average temperature will cause ice to melt and sea levels to rise making flooding more common
  • Some animals may migrate away from their habitats and may become extinct if they can’t adapt to new conditions - Weather will become more extreme as some areas become more wet and others become more dry
  • More CO2 will dissolve into the ocean making it slightly more acidic. The change in pH can kill organisms
200
Q

SC21d - How can the impact of climate change be reduced and what are the drawbacks?

A
  • Using renewable energy as they release little or no greenhouse gases. However this may not be enough
  • Global engineering solutions such as reflecting sunlight or carbon capture. However some countries may not help and delicate ecosystems can be disrupted
  • Helping locals to adapt to new conditions e.g. new irrigation systems and flood defenses how ever this can destroy natural habitats and may not work
201
Q

SC21b - What is the test for Carbon dioxide?

A

When Carbon dioxide is bubbled through limewater, it will cause it to turn from colourless to cloudy/milky

202
Q

SC22a - What is a hydrocarbon?

A

A molecular compound containing only hydrogen and carbon atoms

203
Q

SC22a - What is the functional group of an alkane?

A

Trick question. They have no functional group

204
Q

SC22a - What is the general formula of an alkane?

A

CnH2n+2

205
Q

SC22a - What are the first four prefixes for all the homologus serieses?

A
  1. Meth- (Don’t do drugs)
  2. Eth-
  3. Prop-
  4. But-
206
Q

SC22a - According to the IUPAC, how are hydrocarbons (and many other molecule types) named?

A
  • Prefix showing its number (e.g. Meth- is 1)
  • Suffix showing its homologous series (e.g -ane is alkane)
207
Q

SC22a - Why is an alkane saturated?

A

It only contains single bonds between carbon bonds meaning it can’t open out and bond to more atoms

208
Q

SC22a - What are the displayed and molecular formulae of the first four alkanes?

A
209
Q

SC22a - What is a functional group?

A

The part of a molecule that identifieis it with its specific functional group and is responsible for its chemical properties

(e.g all carboxylic acids have COOH )

210
Q

SC22a - What is the functional group of an alkene?

A

All alkenes contain one double covalent bond between two carbon atoms

211
Q

SC22a - What is the general formula of an alkene?

A

CnH2n

212
Q

SC22a - Why is there no ‘methene’ ?

A

A meth- alkene would have 1 carbon atom but to be an alkene, it would need a double bond between carbons, which can’t happen, unless there are 2+ carbon atoms

213
Q

SC22a - Why is an alkene unsaturated?

A

It contains a double covalent bond between two carbon atoms, meaning that the bond can be opened out and another atom can bond to it.

214
Q

SC22a - What are the molecular and displayed formula of the first 3 alkenes (remember there isn’t a ‘methene’)

A
215
Q

SC22a - What is an isomer?

A

The same molecule with their functional group placed in different places.

e.g. below is but-1-ene (as the group is in it’s first possible position) and but-2-ene (with the group in the second position)

216
Q

SC22a - Why are there no isomers of ethene and propene?

A
  • Ethene only has 2 carbon atoms and so the double bond can only be in one place
  • Propene has 3 carbon atoms and so the double bonds can be in 2 places however, positioning them in these two places would make reflections of the same molecule
217
Q

SC22b - How do alkanes and alkenes react in combustion?

A
  • When heated up sufficiently, hydrocarbons will oxidise, and combust, reacting with the oxygen in the air and releasing energy
  • When sufficient oxygen is present, all the hydrocarbon will oxidise (complete combustion)
    • Hydrocarbon + Oxygen → Carbon dioxide + water
  • When there is a lack of oxygen, not all of the hydrocarbon will oxidise (incomplete combustion) Carbon monoxide and/or carbon aswell, instead of just carbon dioxide
218
Q

SC22b - How can you tell if a chemical is an alkene or an alkane?

A
  • When placed in and mixed with bromine water, an alkane won’t react and no change will be observed
  • However, the double bond in an alkene, will open out and react with the bromine water taking it out of the water and it goes from orange-brown to colourless
219
Q

SC22b - What colour is bromine water?

A

Orange-brown

220
Q

SC22b - What is an addition reaction

A

When more than one reactant reacts to form a larger product and no other products

221
Q

SC22b - What is the word equation for the addition reaction between ethene and bromine water?

A

Ethene + Bromine water → 1,2 dibromoethane

(Don’t know if this is required knowledge)

222
Q

SC23a - What are the uses of ethanol?

A
  • Alcoholic beverages
  • Fuel for vehicles
  • Material in raw industry
223
Q

SC23a - What is ethanol made from?

A
  • Sugars. These are small soluble substances that belong to a group called carbohydrates
  • Seeds contain a carb called starch (a long polymer).
  • Germinating seeds allows enzymes to break down the starch into sugars
  • Fermentation uses enzymes in yeast to turn the sugars into ethanol
224
Q

SC23a - What plants are used to make different alcoholic beverages?

A
  • Beer - Barley seeds
  • Wine - Grapes
  • Whisky - Barley seeds
  • Vodka - Wheat seeds
225
Q

SC23a - Describe the fermentation process of ethanol

A
  • Glucose → Ethanol + Carbon dioxide
  • Yeast containing enzymes that will turn the glucose solution into ethanol
  • Heat source keeps the solution at the optimum temperature of around 25 C
  • Air lock lets out carbon dioxide, but doesn’t let any oxygen in, allowing anaerobic respiration to occur
226
Q

SC23a - What is the problem with the fermentation process and how is this overcome?

A

Only alcohol of 15% concentration can be produced (or else the yeast enzymes will be killed). So, fractional distillation is used to obtain high concentrations of alcohol.

Ethanol’s b.p. of 78 C is less than water and so it evapourates first and condenses into a distillate of high conc. ethanol

227
Q

SC23b - What is an organic compound?

A

A compound with a central framework of carbon atoms but with hydrogen and other atoms attached

228
Q

SC23b - What is the functional group of the alcohols homologous series?

A

-OH atoms on the end of the compound

229
Q

SC23b - What is the general formula of alcohols?

A

CnH2n+1

230
Q

SC22a - What are the first four alkanes?

A
  • Methane
  • Ethane
  • Propane
  • Butane
  • -ane is prefix
231
Q

SC22a - What are the first three alkenes?

A
  • Ethene
  • Propene
  • Butene
  • -ene is prefix
232
Q

SC23b - What are the first four alcohols?

A
  • Methanol
  • Ethanol
  • Propanol
  • Butanol
  • -anol is prefix
233
Q

SC23c - What are the first four carboxylic acids?

A
  • Methanoic acid
  • Ethanoic acid
  • Propanoic acid
  • Butanoic acid
  • -anoic acid is prefix
234
Q

SC23b - What is the displayed and molecular formula of the first four alcohols

A
235
Q

SC23b - What are the chemical properties of the alcohols?

A
  • Produce carbon dioxide + water during complete combustion
  • Can be oxidised to produce carboxylic acids
  • React with reactive metals and produces hydrogen (among other products)
236
Q

SC23b - What is the trend of reactivity for alcohols?

A

The longer the chain, the less vigorously they will react (for example less bubble produced when sodium is added)

237
Q

SC23b - What are some uses of alcohols?

A
  • Medical products
  • Fuels
  • Varnishes
  • Cosmetics
238
Q

SC23b - Describe the trend in energy stored per Litre for alcohols

A

Longer chains store more energy per litre, making them more effective fuels

239
Q

SC23b - What is so advantageous about alcohol fuel?

A

They can be made from renewable sources such as fermenting plant cellulose using bacteria. (Currently methanol and ethanol fuels are being used)

240
Q

SC23c - Why does wine turn into vinegar when left out?

A

The ethanol oxidises and turns into ethanoic acid (a type of vinegar)

241
Q

SC23c - Describe the process of the oxidisation of an alcohol

A
  • The Oxygen molecule from the air collides with the functional group of the alcohol
  • Two hydrogen molecules are ‘knocked off’ and bond with an oxygen to form water
  • Meanwhile the other oxygen bonds to the carbon forming a carboxylic acid
242
Q

SC23c - What is the functional group of a carboxylic acid?

A

-COOH at the end

243
Q

SC23c - What is the displayed and molecular formula of the first four carboxylic acids?

A
244
Q

SC23c - What is the general formula of carboxylic acids?

A

CnH2n+1COOH

[Ok real talk guys. The above general formula is the one you need to know. However, unlike in other general formulas, the ‘n’ value isn’t the number in the series (idk what it is). So if you want a general formula based off number in series, Cn-1H2n-1COOH but if they ever ask in the exam what the general formula, it is the top one as that is the spec one]

245
Q

SC23c - What are oxidising agents and why are they used?

A
  • The natural process of oxidisation of an alcohol is time consuming and uncontrollable.
  • Instead, reacting an alcohol with an compound that contains oxygen is more effective.

e.g Propanol + (hot) copper oxide → Propanoic acid + Water + Copper

246
Q

SC23c - What are the chemical properties of carboxylic acids?

A
  • Form solutions with pH <7 (if soluble)
  • React with metals to from salt and hydrogen
  • React with bases to form salt and water
  • React with carbonates to form salt water and carbon dioxide
247
Q

SC23c - What gives carboxylic acids their acidity?

A

The -COOH group has a H+ ion which makes it acidic

248
Q

SC23c - How can vinegar be used to test for chalk/limestone?

A

Chalk/limestone are carbonates and so when vinegar is added, the ethanoic acid will fizz due the presence of carbon dioxide produced from the reaction

249
Q

SC23c - Describe the trend in acidity of carboxylic acids

A

The longer the chain the less acidic (higher pH)

250
Q

SC24a - What are plastics made from?

A

Polymers

251
Q

SC24a - What is a polymer?

A

A long molecule made up of lots of tiny molecules called monomers

252
Q

SC24a - What is polymerisation?

A

The process by which many monomers are joined together to form a polymer

253
Q

SC24a - What is special about the relative atomic mass of polymers?

A

They can be very large due to having millions of molecules. As they can be any lengths, they are never given

254
Q

SC24a - What is addition polymerisation?

A

When many of the same monomer are added together to form one polymer and no other products

255
Q

SC24a - Describe the addition polymerisation of ethene into poly(ethene)

A
256
Q

SC24a - What is the repeating unit of a polymerisation equation?

A

It shows how the monomer has changed and how it repeats throughout the polymer chain

257
Q

SC24a - What is a synthetic polymer?

A

One manufactured in a lab/factory

258
Q

SC24a - What are some examples of naturally occurring polymers?

A
  • Starch (made of glucose)
  • Protein (made of amino acids)
  • DNA (made from nucelotides)
259
Q

SC24b - How are polymers named?

A

Poly(name of monomer)

260
Q

SC24b - Why can alkenes be used to make polymers?

A

They contain a double carbon bond that can be opened out to bond to more monomers

261
Q

SC24b - What is key to remember when drawing repeating units?

A

Make sure the bond lines go through the brackets to show that it can continue to bond

262
Q

SC24b - Properties and uses of Poly(ethene)

A
  • Common name: Polythene
  • Properties: Flexible, cheap
  • Uses: Plastic bags, cling film
263
Q

SC24b - Properties and uses of Poly(propene)

A
  • Common name: polypropylene (wtf is the common name longer)
  • Properties: Flexible, shatter resistant
  • Uses: Buckets and bowls, ropes
264
Q

SC24b - Properties and uses of Poly(chloroethene)

A
  • Common names: polyvinyl chloride PVC
  • Properties: Tough, good insulator
  • Uses: Pipes, window frames
265
Q

SC24b - Properties and uses of Poly(tetrafluorene)

A
  • Common names: PTFE, Teflontm
  • Properties: Tough, slippery
  • Uses: Burette taps, non-stick coating
266
Q

SC24c - What is a polyester?

A

A synthetic polymer made by condensation polymerisation. It contains many ester links

267
Q

SC24c - What is the functional group of an ester?

A
268
Q

SC24c - How are esters formed?

A
  • When a carboxylic acid is reacted with an alcohol

Carboxylic acid + alcohol → ester + water

269
Q

SC24c - Why is an ester-creating reaction considered a condensation reaction?

A

Water is produced

270
Q

SC24c - How would ethanoic acid and ethanol react to form an ester?

A

The -OH from the ethanoic acid and the H from the ethanol will break off and react to form water. Then, the C on the acid will bond with the O from the alcohol

271
Q

SC24c - What is required to form a polyester?

A

Each monomer has a functional group on BOTH sides

e.g. below is ethanoic acid and ethanol

272
Q

SC24c - What will a polymer equation for the condensation polymerisation of ethanoic acid and ethanol?

A

This process is something that should be practiced as you need to practice drawing it out

273
Q

SC24d - What is the problem with the process to make synthetic polymers?

A

They are obtained from crude oil which is a non-renewable finite resource and will eventually run out

274
Q

SC24d - What does biodegradable mean?

A

It can rot as mircrobes can break it down

275
Q

SC24d - What are the pros and cons of synthetic polymers being non-biodegradable?

A

+ They can be used for a long time

  • They don’t rot when thrown away
276
Q

SC24d - What are the pros and cons of incinerating plastic rubbish?

A

+ Takes up less space

+ Energy released can be used to generate electricity

  • Produces Carbon dioxide (GH gas)
  • Some plastics produce toxic substances when burnt (these can be removed but forms toxic ash which needs to be disposed)
277
Q

SC24d - How can we reduce the amount of waste going to incinerators and landfill sites?

A

Re-using and recycling materials

278
Q

SC24d - Describe the process of recycling polymers

A
  • Collection (kerbside or recycle points)
  • Sorting (can be expensive and time consuming)
  • Disposal of un-recyclable wast to landfill sites
  • Clean polymers and grind to chippings
  • Purify chippings
  • Melt and remould chippings
279
Q

SC24d - How is the sorting process of recycling made easier?

A

Labels for each type of polymer

280
Q

SC25c - How do you test for carbonate ions?

A

Add dilute hydrochloric acid to the sampleIf it does contain a carbonate, this will cause carbon dioxide to be produced This will cause effervesenceTo make sure this is carbon dioxide, bubble the gas produced through limewaterIf carbon dioxide is present, limewater will turn colourless to cloudy.milky

281
Q

SC25a - What colour do Lithium (Li+) ions turn in a flame test?

A

(Bright) Red

[Lith-le red riding hood]

282
Q

SC25a - What colour do Sodium (Na+) ions turn in a flame test?

A

Yellow

283
Q

SC25a - What colour do Potassium (K+) ions turn in a flame test?

A

Lilac

P̶u̶r̶p̶l̶e̶.̶ ̶A̶H̶H̶H̶H̶H̶ ̶I̶’̶M̶ ̶S̶O̶R̶R̶Y̶ ̶O̶K̶ ̶O̶K̶ ̶I̶T̶S̶ ̶N̶O̶T̶ ̶P̶U̶R̶P̶L̶E̶

284
Q

SC25a - What colour do Calcium (Ca2+) ions turn in a flame test?

A

Orange-red

285
Q

SC25a - What colour do Copper (Cu+) ions turn in a flame test?

A

Blue-Green

286
Q

SC25a - What are the 3 main steps in conducting a flame test?

A
  • Light a Bunsen burner to a strong blue flame
  • Pick up a sample of the substance with a small wire loop
  • Hold the sample into the edge of the flame and observe the colour
287
Q

SC25a - Why may the flame test loop be a platinum one?

A
  • It has a high melting point and so won’t melt
  • It is inert and so won’t react It doesn’t produce/affect a flame colour
288
Q

SC25a - Why may a nichrome alloy be used as a wire loop for a flame test?

A
  • It is cheaper
  • However, it produces a light orange flame that could affect the results
289
Q

SC25a - What is flame photometry?

A
  • When a solution containing the metal ions creates a flame and the light intensity is measured by a computer.
  • This allows it to have quantitative and comparable data
290
Q

SC25a - What are the main three advantages of photometry over flame tests?

A
  • Sensitivity: Much smaller sample sizes can be used
  • Accuracy: They give results closer to the true value
  • Speed: They occur with more quickness [look at me defining speed like a pro]
291
Q

SC25a - What is a callibration curve?

A
  • It shows the light intensity produced by metal ions in different concentrations of solutions
  • It is created by using standard solutions of known concentrations
  • This allows data comparison to be accurate
292
Q

SC25a - What can flame photometers do to the light emitted by a flame?

A

They can separate the light produced into a spectrum of different colours (wavelengths) of light

293
Q

SC25a - What is an emission spectrum?

A
  • Metal ions each produce their own unique combination of different wavelengths of light
  • This different colours are the emission spectrum of an ion and can be used to identify ions
  • Together, these different colours will produce the one colour seen in the flame test
294
Q

SC25b - How do you conduct a precipitate reaction to identify metal ions?

A
  • A few drops of sodium hydroxide are added to a solution containing metal ions
  • The metal and the hydroxide will react to form metal hydroxide
  • This will be insoluble and form a precipitate of a colour that can be used to identify the metal
295
Q

SC25b - What colour precipitate do Iron(II) (Fe2+) ions form?

A

Green

296
Q

SC25b - What colour precipitate do Iron(III) (Fe3+) ions form?

A

Brown

297
Q

SC25b - What colour precipitate do Copper (Cu2+) ions form?

A

Blue

298
Q

SC25b - What colour precipitate do Calcium (Ca2+) ions form?

A

White

299
Q

SC25b - What colour precipitate do Aluminium (Al3+) ions form?

A

White

300
Q

SC25b - What is the problem with the precipitate test for calcium and aluminium and how is this overcome?

A
  • Both calcium and aluminium ions will produce a whit precipitate when reacted with sodium hydroxide.
  • Thus, a distinguishing test is required In this case, excess sodium hydroxide is added
  • For aluminium ions, this causes the precipitate to eventually turn colourless
301
Q

SC25b - What is the test for ammonium ions?

A
  • Dilute sodium hydroxide solution is added which produces ammonia gas
  • Ammonia gas has a characteristic sharp smell but a confirmatory test is needed to be sure
  • Ammonia gas turns damp red litmus paper blue
302
Q

SC25c - How do you test for carbonate ions?

A
  • Add dilute hydrochloric acid to the sample If it does contain a carbonate, this will cause carbon dioxide to be produced
  • This will cause effervesence
  • To make sure this is carbon dioxide, bubble the gas produced through limewater
  • If carbon dioxide is present, limewater will turn colourless to cloudy.milky
303
Q

SC25c - How do you test for sulfate ions?

A
  • Add some dilute hydrochloric acid to the solution
  • Then add barium chloride If sulfate ions are present, this will produce a white precipitate of (insoluble) barium sulfate
304
Q

SC25c - Why is hydrochloric acid added when testing for sulfate ions?

A

To remove any carbonate ions and therefore eliminate the chance of a false positive result

305
Q

SC25c - How do you test for halide ions?

A
  • Add some dilute nitric acid to your sample
  • Add some silver nitrate solution
  • Observe the colour of the precipitate formed and compare to check what ion was present
306
Q

SC25c - What colour precipitate do Chloride (Cl-) ions form?

A

White

307
Q

SC25c - What colour precipitate do Bromide (Br-) ions form?

A

Cream

308
Q

SC25c - What colour precipitate do Iodide (I-) ions form?

A

Yellow

Koky chem (24 decks)

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