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Koky chem > Paper 1 Collection ✓ > Flashcards

Paper 1 Collection ✓ Flashcards

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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 behind the 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 on a 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

They can only conduct when molten or aqueous:

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

  1. Charged
  2. Free to move

Ionic compounds have charged particles (ions). These are only free to move when the compound is 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 as the layers slide over each other
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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

SC8a - All solutions are one of what three things?

A
  • Acidic
  • Neutral
  • Alkaline
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74
Q

SC8a - What determines if a solution is acidic or alkali?

A
  • The concentration of hydroxide (OH-) ions and hydrogen (H+) ions when dissolved in water.
  • An even balance of both will lead to all of them forming water (OH- + H+ → H2O) and an excess of neither.
  • An excess of H+ ions makes a solution acidic and an excess of OH- ions makes a solution alkaline.
  • The concentration of theses ions determiens the pH of a solution
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75
Q

SC8b - Describe how a solution can be concentrated or dilute

A
  • A concentrated solution contains a high concentration of excess ions (more per unit volumes)
  • A dilute solution contains a low concentration of excess ions (less per unit volumes)
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76
Q

SC8b - Describe how a solution can be strong or weak

A
  • When a strong acid/alkali is dissloved in water, their molecules fully dissociate (break up) producing a high concentration of ions
  • When a weak acid/alkali is dissolved in water, their molecules don’t fully dissociate and so they produce a low concentration of ions
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77
Q

SC8c - What is a base?

A
  • A base is a substance that neutralises an acid.
  • Base(s) + acid(aq) → salt(aq) + water(l)
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78
Q

SC8c - Describe how neutralisation occurs in terms of ions.

A
  • The acid has excess H+ ions and the base has excess OH- ions
  • These bond to form water [H+ + OH- → H2O]
  • The other elements in the base and the acid bond to form a salt
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79
Q

SC8c CP - Describe how to prepare copper sulfate from copper oxide and sulfuric acid.

A
  • Mix copper oxide into a beaker of hydrochloric acid till it is in excess
  • Gently warm the mixture to speed up the reaction
  • Filter to remove the excess copper oxide
  • Heat up the solution in an evapourating basin over water on a bunsen burner
  • Right before all the liquid has evapourated, remove it from the heat and leave it to evapourate naturally
  • The longer it takes, the larger the crystals of copper sulfate formed
80
Q

SC8d - What is a soluble base?

A

An alkali

81
Q

SC8d CP - Investigate how the pH of an hydrochloric acid changes based on the amount of calcium hydroxide in it

A
  • Usign a measuring cylinder, add 50cm³ of hydrochloric acid to a beaker
  • Keep pieces of universal indicator paper on white tiles
  • Dip the end of the glass rod into the acid and dab it onto the paper
  • Estimate the pH of it and dab the rod dry
  • Add 0.3g of calcium hydroxide powder to the acid and then repeat this
  • Keep adding 0.3g at a time recording the the pH each time until you’ve added 2.4g
  • Draw out a graph for the values of pH and calcium carbonate added
82
Q

SC8f - Acid + Metal →

A

Acid + Metal →Salt + Hydrogen

83
Q

SC8f - Acid + Carbonate →

A

Acid + Carbonate → Salt + Water + Carbon Dioxide

84
Q

SC8f - How do you work out the ionic equation of a metal + acid reaction?

A
  • [Mg can be replaced with any metal but may be balance differentyl]
  • Mg(s) + 2H+(aq)→ Mg2+(aq) + H2(g)
  • The other ions (sulfate, chloride etc.) are spectator ions as they don’t change form either side of the equation
85
Q

SC8f - Using the ionic equation

Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)

How do you work out the half equations?

A

Mg(s) → Mg2+(aq) + 2e-

2H+ (aq) + 2e- → H2(g)

86
Q

SC8e - What method can be used to work out how much acid to use to obtain pure dry crystals of salt?

A

Repeated titration (method in SC14) followed by crystallisation using the results.

87
Q

SC8g - What is a precipitate reaction?

A

When two soluble substances in solutions react and form an insolube precipitate as one of its products

88
Q

SC8g - What are the rules for solubility?

A
  • All PANS are soluble (potassium, ammonium, nitrates and sodium)
  • Chlorides apart from silver and lead are soluble
  • Sulfates apart from lead, barium and calcium are soluble
  • The only carbonates and hydroxides that are soluble are the PANS
89
Q

SC8g - What happens when two solutions containing soluble salts are reacted?

A
  • The ions from the salt switch.
  • e.g copper sulfate + potassium carbonate → copper carbonate + potassium sulfate
90
Q

SC8g - How do you form an insoluble salt from silver nitrate and sodium chloride?

A
  • Pour some silver nitrate solution into some sodium chloride solution in a beaker
  • This will react forming a precipitate of silver chloride
  • Use a filter funnel with filter paper to filter this out
  • Wash the precipitate with distilled water
  • Remove the filter paper containing the salt and place in a warm oven to dry
91
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
92
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
93
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
94
Q

SC9c - What is the molar mass formula?

A

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

95
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)

96
Q

SC9b - What is a dm³ equal to?

A

1L = 1000 cm³

97
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
98
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
99
Q

SC9c - What is avrogodos constant?

A

The amount of particles in a mole 6.02x1023

100
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
101
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
102
Q

SC9c - What is stochiometry?

A

The ratio of moles in a reaction

103
Q

SC10a - Define electrolysis?

A

The breaking down of an electrolyte using electricity (d.c supply)

104
Q

SC10a - Describe the relationship between positive and negative ions and their electrode, naming them.

A
  • (Positive) Cations are attracted to the (negative) Cathode
  • (Negative) Anions are attracted to the (positive) Anode
105
Q

SC10a - Why is an electrolyte able to conduct electricity?

A
  • When an ionic solid is melted down or dissolved in water, its ionic bonds breaking meaning that the ions inside are now free to move.
  • This allows the electrolyte to conduct electricity.
106
Q

SC10a - Describe the setup for an electrolysis exmperiment.

A
  • Two electrodes (cathode and anode) are connected to a d.c supply.
  • They are also placed in the electrolyte (which is either molten or aqueous).
107
Q

SC10a - At which electrodes do oxidation and reduction take place and how do these processes affect ions?

A
  • Oxidation is the loss of electrons and takes place at the anode. Reduction is the gain of electrons and takes place at the cathode.
  • OIL RIG:
  • Oxidation Is Loss;
  • Reduction Is Gain
108
Q

SC10a - Use half equations to display the oxidation and reduction of Zinc and Chlorine during electrolysis.

A

Zn2+ + 2e- → Zn (Reduction)

2Cl- → Cl2 + 2e- (Oxidation)

109
Q

SC10a CP - Descirbe what you would expect to see when conducting the electrolysis of copper chloride solution using graphite (inert) electrodes.

A
  • The cathode will be coated with a brownish layer.
  • This shows copper is being produced
  • At the anode there will be bubbles.
  • This indicates that a gas is being produced
  • If you hold a damp blue litmus paper near this, it will turn red and then bleach white.
  • This indicates that the gas produced is chlorine
110
Q

SC10a CP - Descirbe what you would expect to see when conducting the electrolysis of copper chloride solution using an impure copper anode and a pure copper cathode.

A
  • The anode will appear to be smaller (it will have lost mass)
  • The cathode will appear bigger (it has gained mass)
  • Under the anode, there will be a collection of impurities that have settled
  • This shows that the pure copper ions have migrated from the anode to the cathode
111
Q

SC10b - How can you predict the products of electrolysis?

A
  • When electrolysing a solution, water will always be present
  • This means H+ and OH- ions are always present
  • At the cathode, the metal can only be produced if it is less reactive than H+ (Tin and below on reactivity series)
  • At the anode Oxygen will always be produced unelss the negative ion is a halide (has a charge of 1-)
  • If the electrolyte is molten, the components of the electrolyte will be produced
112
Q

SC11a - List the resctivity series [with a way to remember it]

A
  • Pop Potassium
  • Stars Sodium
  • Can Calcium
  • Make Magnesium
  • Absolute Aluminium
  • Crazy (Carbon)
  • Zillions Zinc
  • If Iron
  • Tiny Tin
  • Little Lead
  • Children Copper
  • Spend Silver
  • Good Gold
  • Pennies Platinum
113
Q

SC11a - How do potassium, calcium and sodium react with water and dilute acids?

A
  • Reacts with cold water to from hydrogen and metal hydroxide
  • Reacts violently with acid
114
Q

SC11a - How do magnesium, aluminium, zinc and iron react with water and dilute acids?

A
  • Reacts very slowly if at all when with cold water
  • But reacts with steam to form metal oxide and hydrogen
  • Reacts with acid to form hydrogen and salt solution
115
Q

SC11a - How do copper, silver, gold and platinum react with water and dilute acids?

A

They don’t as they are inert in their pure form.

116
Q

SC11a - What is a displacement reaction?

A
  • A reaction in which a more reactive element displaces a less reactive element from a compound.
  • e.g. Zn + CuSO4 → ZnSO4 + Cu
117
Q

SC11a - A displacement reaction is also another type of reaction. What is this and how can you show this?

A

A redox reaction as the charge on the metals switch around. e.g.in Zn + CuSO4 -> ZnSO4 + Cuthe ionic euation shows thatZn + Cu2+ -> Zn2+ + Cu

118
Q

SC11b - What are the three ways you can extract metals and how do these relate to their position on the reactivity series?

A
  • Found uncombined in the earth’s crust.
    • This applies to elements gold and lower in the reactivity series
  • Extacted by heating an ore with carbon.
    • This is for elements less reactive than carbon or else carbon can’t displace it
  • Electrolysis of molten compound.
    • This is very expensive so only used for aluminium and upwards as they cannot be ehated with carbon to be extracted
119
Q

SC11b - What is an ore?

A

A rock that contains enough of a metal to extract it for a profit.

120
Q

SC11b - What are the two biological methods of extraction?

A
  • Phytoextraction:
    • Growing plants on lands that contain the desired matal so that they absorb it.
    • These are then burned and the metal is obtained fromt their ashes
  • Bioleaching:
    • Bacteria is grown on low-grade(uneconomical) ore.
    • This forms a leachate (solution containing the desired metal compound)
    • The copper is extracted by displacing it with scrap iron.
121
Q

SC11b - What are the advantages and disadvantages of using bioleaching?

A

Pros:

  • No harmful gases produced
  • Less landscape damage than mining
  • Conserves supplies of high grade ores
  • Doesn’t require high temeratures

Cons:

  • Very slow
  • Toxic substances can be produced which damage the environment
122
Q

SC11b - What are the advantages and disadvantages of using phytoextraction?

A

Pros:

  • No harmful gases produced
  • Less landscape damage than mining
  • Conserves supplies of high grade ores
  • Can extract minerals from contaminated soils

Cons:

  • Very slow
  • More expensive than mining some ores
  • Plant growth is dependant on weather conditions
123
Q

SC11c - What are oxidation, reduction and redox reactions in terms of oxygen?

A
  • Oxidation is the gain of oxygen
  • Reduction is the loss of oxygen
  • A redox reaction is a reaction in which a substance is oxidised and another is reduced
124
Q

SC11c - What is corrosion?

A

When a metal reacts with oxygen (oxidises) making it weaker over time

125
Q

SC11c - How is rusting different to corrosion?

A

Rusting occurs when iron/steel reacts with oxygen and water.

126
Q

SC11c - Why don’t some metals such as aluminium corrode very quickly, despite being very reactive?

A

They form a protective layer of tarnish stopping any further corrosion

127
Q

SC11d - What are the advantages of recylcing metals?

A
  • Natural resources of ores will last longer
  • Less need to mine and harmful side effects from this
  • Less pollution from extraction
  • For many metals this takes less energy
  • Less waste metals at landfill sites
128
Q

SC11d - What are the disadvantages of recycling metals?

A
  • Costs of energy is high to collect, transport and sort are high
  • Sometimes it is more expensive to recycle metals than to extract more
129
Q

SC11d - What is a life cycle assessment and what are its uses?

A

A life cycle assessment is an assessment to work out the environmental impact of the obtaining, manufacturing, use and disposal of a product.

It can be used to work out:

  • Which materials are better to use for manufacturing
  • Whether its more beneficial to recycle or not
130
Q

SC12a - What is a reversible reaction?

A

A reaction where the products can react again to reform the reactants

131
Q

SC12a - What symbol would show that a reaction is reversible?

A

⇌ : The double arrow

132
Q

SC12a - In a reversible reaction how does the speed of the forward reaction and backward reaction change over time?

A
  • The forward reaction starts fast and gets slower over time.
  • The backward reaction starts slow and gets faster over time.
133
Q

SC12a - Define Dynamic Equilibrium

A

When the forward and backward reactions in reversible reaction occur at the same rate.

134
Q

SC12a - What happens to the amount of products and reactants produced once a reaction has reached Dynamic Equilibrium?

A

They stop changing (increasing or decreasing)

135
Q

SC12a - What is required for Dynamic Equilibrium to be achieved, and why?

A
  • A closed system.
  • In an open system fluids can escape and equilibrium cannot be reached
136
Q

SC12a - What is the name and the chemical formula of the process that creates ammonia?

A
  • The Harber Process:
  • N2(g) + 3H2(g) ⇌ 2NH3(g)
137
Q

SC12a - What is the temperature, pressure and catalyst used during the Harber Process?

A
  • T: 450°
  • P: 200 Atmospheres (atm)
  • C: Iron Catalyst
138
Q

SC13a - Where are Transition Metals found, on the periodic table?

A

In the middle of the periodic table, between groups 2 and 3

139
Q

SC13a - Describe some typical physical properties of transition metals.

A
  • Malleable
  • Ductile
  • Lustrous (when polished)
  • Good conductors of heat and electricity
  • High melting points and densities (compared to groups 1 and 2)
140
Q

SC13a - Describe some typical chemical properties of transition metals.

A
  • Usually form coloured compounds (colour decided by the ion involved e.g. copper forms blue compounds)
  • Chemical catalysts
141
Q

SC13b - What is corrosion?

A

When a metal continuously oxidises over time becoming weaker

142
Q

SC13b - What are the two requirements for corrosion to occur?

A

Oxygen (in air typically) and water

143
Q

SC13b - What is rusting?

A

The corrosion of Iron (or steel)

144
Q

SC13b - What is oxidation in terms of electrons and oxygen?

A

The loss of electrons and/or the gain of oxygen

145
Q

SC13b - How does sacrificial protection work?

A
  • A more reactive metal is attached to Iron or Steel.
  • The oxygen and water are going to react with the more reactive metal instead, protecting the iron and steel
146
Q

SC13b - Which metals are typically involved in sacrificial protection?

A

Zinc or magnesium, protecting iron or steel from rusting

147
Q

SC13b - What makes a metal more or less reactive?

A

How easily its able to loose its outer shell electrons (this is a combination of how many there are and how far away from the nucleus they are)

148
Q

SC13c - For what two main reasons may a metal be electroplated?

A
  • To improve its appearance
  • To improve its resistance to corrosion or rusting
149
Q

SC13c - What process is used to electroplate a metal?

A

Electrolysis

150
Q

SC13c - What is galvanising?

A

Coating iron or steel with zinc to protect it.

151
Q

SC13c - Which two methods can be used to galvanise an object?

A

Dipping it in molten zinc or electroplating

152
Q

SC13c - When electroplating, what would you use as the anode and cathode?

A
  • Cathode will be the object you are plating
  • Anode will be the metal you are plating it with.
153
Q

SC13d - What is an alloy?

A

A mixture of a metal with one or more other (not necessarily metal) elements

154
Q

SC13d - Why are alloys stronger than pure metals [4 marks]

A
  • In a pure metal all the atoms are the same size in a regular structure
  • his allows layers to slide over each other easily
  • In an alloy, the atoms are different sizes in an irregular structure
  • This means layers cannot slide over each other as easily
155
Q

SC13e - Name some uses of gold copper and aluminium linked to their properties that suit its use.

A

Gold:

  • Memory chips - Good conductor of electricity
  • Jewellery - Lustrous

Copper:

  • Wires - Ductile
  • Coins - Cheap and malleable

Aluminium:

  • Overhead cables - Low density
156
Q

SC13e - Name some uses of magnalium, brass and nitinol linked to their properties that suit its use.

A

Magnalium (Magnesium and aluminium):

  • Lightweight mechanical parts
    • Low density
    • High strength

Brass (Copper and zinc):

  • Plug in points
    • Corrosion resistant
    • Good conductor of electricity

Nitinol (Nickel and Titanium):

  • Braces and glasses frames
    • Shape memory allows it to have 2 shapes depending on pressure or temperature.
157
Q

SC14a - What is the difference between actual and theoretical yield?

A
  • Theoretical yield: The yield you would expect to get based off the ratio of moles
  • Actual yield: The yield you get once the experiment has been conducted
158
Q

SC14a - How do you calculate percentage yield?

A

Percentage yield compares actual yield to theoretical yield

PY = (AY ÷ TY) x 100

159
Q

SC14a - What are the reasons that actual yield may be less than theoreticla yield?

A
  • The reaction has not been left for long enough/has reached equilibrium
  • Practical losses such as liquids being left in containers and gases escaping
  • Unwanted side reactions taking palce can use up some reactants to make a different product
160
Q

SC14a - Why is a higher percentage yield better?

A

It means there has been a more efficient use of the products

161
Q

SC14b - How do you work out atom economy and what does it show you?

A
  • It shows you the perentage of atoms that have gone into making useful products and how many atoms you are wasting
  • Allows you to compare and work out the most efficient way fo making a product
  • Atom economy = (Mr of useful product(s) ÷ Sum of Mr of reactants) x 100
  • Mr can also be Ar
162
Q

SC14b - What is one way of improving atom economy?

A

Finding uses for the by-products of the reaction

163
Q

SC14c - How do you convert concentrations from mol/dm³ and g/dm³

A

Using the molar mass forumla

mol/dm³ = (g/dm³) ÷ (m/dm³)

164
Q

SC14d - How do you work out the volume or concentration of an alkali needed to neutralise a given acid?

A
  • Firstly work out the balanced equation (which may already be given) and work out the molar ratio of the acid and alkali reactants
  • In a 1:1 ratio, the concentrations will be inversely proportionate to the volumes used (will multiply to make the same number)
  • If not then multiply the concentration and volume of the acid.
  • Divide it by its side of the ratio and multiply it by the other
  • This will give you the moles involved
  • Divide this by either the concentration or volume of the alkali to find the other
165
Q

SC14d CP - Describe the method used to carry out an acid-alkali titration with hydrochloric acid (HCl) and 25cm³ of Sodium Hydroxide solution (NaOH)

A
  • Use a pipette to measure out 25cm³ of sodium hydroxide and empty this solution into a conical flask
  • Place the conical flask on a white tile (So you can see the colour change later on)
  • Wash out a burette with hydrochloric acid and fill it up to top with this.
  • Record the inital reading on the burette (from the bottom on the meniscus)
  • Add a few drops of indicator (methyl orange or phenolphthalein) to the conical flask and move this and the white tile under the burette
  • Open the tap of the buretted letting the acid flow through. Constantly swirl the flask
  • When you first see a colour change, slow down the tap
  • For phenolphthalein this will be pink to clourless; For methyl orange this will be yellow to red
  • Once the colour has changed and won’t change back, stop the tap and read the value on the burette (from the bottom of the meniscus)
  • Work out how much acid has been used
  • Repeat multiple times and take an average of the concordant results
166
Q

SC14e - What is the Molar gas volume at rtp (room temperature and pressure)

A

24dm³

24 000 cm³

167
Q

SC14e - What is the formula for the moles in a gas?

A

Moles = Volume ÷ Molar gas volume (24dm³ at rtp)

168
Q

SC15a - Through what do plants absorb mineral ions?

A

Their root hair cells

169
Q

SC15a - Why must fertilisers contain soluble compounds?

A

Root hair cells can only absorb mineral ions that are dissolved in water

170
Q

SC15a - Which three elements are featured in fertilisers?

A
  • Nitrogen
  • Potassium
  • Phosphorus
171
Q

SC15a - What is Ammonium Nitrate an example of?

A

A Nitrogenous (Nitrogen-rich) fertiliser and a source of soluble nitrogen compounds

172
Q

SC15a - How is ammonium nitrate manufactured and how are the materials gathered?

A
  • Ammonium is created through the harber process.
  • Then some ammonia is reacted with oxygen to give nitric acid and water.
  • This nitric acid is reacted with some ammonium solution.
  • This creates ammonium nitrate:
  • NH3 (g) + 2O2 (g) → HNO3 (aq) + H2O (l)
  • NH3 (aq) + HNO3 (aq) →NH4NO3 (aq)
173
Q

SC15a - Where are the reactants for the harber process found?

A
  • Hydrogen from natural gas
  • Nitrogen from the air
174
Q

SC15a - Describe a laboratory preparation of ammonium sulfate.

A
  • Small scale
  • Batch process (only bit by bit)
  • Ammonium solution and dilute sulfuric acid
  • Titration followed by crystallisation
  • Small amount made; equipment is cleaned; repeat
  • Requires frequent maintenance (Hard to automate)
175
Q

SC15a - Describe a factory preparation of ammonium sulfate.

A
  • Large scale
  • Continuous process
  • Raw materials for Ammonia and Sulfuric acid
  • Several stages
  • Large amount made, rarely cleaned
  • Little maintenance required (Easy to automate)
176
Q

SC15a - How is sulfuric acid formed for factory preparation of ammonium sulfate?

A
  • Sulfur and air are reacted to form sulfur trioxide
  • Sulfur trioxide is reacted with water to from Sulfuric acid
177
Q

SC15b - How does an increase in temperature affect the position of equilibrium and rate of attainment?

A
  • Exothermic: Equilibrium shifts to left
  • Endothermic: Equilibrium shifts to right
  • Rate of attainment increased as the particles have more energy causing more frequent collisions.
  • (All are opposite if temperature is decreased)
178
Q

SC15b - How does an increase in pressure affect the position of equilibrium and rate of attainment?

A
  • Equilibrium favors the side with fewer molecules
  • Rate of attainment is increased as the same amount of particles in a smaller space causes more frequent collisions
  • (Opposite if pressure is decreased)
179
Q

SC15b - How does an increase in concentration of the reactant affect the position of equilibrium and rate of attainment?

A
  • Equilibrium shifts towards the products side.
  • Rate of attaimment is increased as there are more particles in the same space and so there are more frequent collisions
  • (Opposite if concentration is decreased)
180
Q

SC15b - How does a catalyst affect the position of equilibrium and rate of attainment?

A
  • Position of equilibrium is unaffected as it effects both sides equally
  • Rate of attainment is increased as the catalyst increases the rate of reaction without being used up
181
Q

SC15b - What natural occurance did the birkeland - eyde process mimick and how was this used to produce Nitric acid?

A
  • Lightning.
  • An electric arc was created between two electrodes causing nitrogen to react with oxygen in the air forming nitrogen monoxide.
  • This was then further reacted with oxygen to form nitrogen dioxide and then dissolved in water to form nitric acid
182
Q

SC15b - Why was the Birkeland-Eyde process bad?

A
  • It was inefficient only producing a yield of 4% nitric acid
  • It cost lots as it took up huge amounts of electricity?
183
Q

SC15b - What process do we now use to obtain Nitric Acid and how does it work?

A

The otswald process:

  • Ammonia + Oxygen ⇌ Nitrogen monoxide + Water
  • Nitrogen Monoxide + Oxygen ⇌ Nitrogen dioxide
  • Nitrogen Dioxide + Oxygen + Water → Nitric Acid
184
Q

SC15b - What is taken into consideration when choosing reaction pathways?

A
  • Availability of raw materials and energy supplies
  • Rate of reaction and equilibrium position
  • Atom economy, yield and usefulness of the by-products
185
Q

SC15b - What are the conditions for stage one of the Otswald Process?

A

220° and 4atm with a hot platinum catalyst

(Ammonia to Nitrogen monoxide is exothermic and there are more molecules on the right)

186
Q

SC16a - What are the components in a chemical cell?

A
  • Two different metals each dipped in a solution of one of their own salts
  • A salt (or ion) bridge to allow the ions to pass from one solution to another and complete the circuit
187
Q

SC16a - How is a potential difference created in a chemical cell and how can its strength be altered?

A
  • Metals push their electrons away with a certain force.
  • The more reactive metal pushes its electrons away to the lesser reactive one which is forced to accept it.
  • This flow of electrons creates a potential difference.
  • Metals that have a greater difference in reactivity will create a larger potential difference.
  • This will also create a greater current as there are more electrons flowing past one point over a given time.
188
Q

SC16a - Why may a battery go flat?

A

One of its reactants have been completely used up and so there are no more elctrons flowing past

189
Q

SC16a - What is a battery?

A

A collection of cells

190
Q

SC16a - How do rechargable batteries work?

A

They are made out of reactants that can be reformed when electricity passes through them.

191
Q

SC16a - What two elements are used in a fuel cell?

A

Hydrogen and Oxygen

192
Q

SC16a - What is used at both sides of the fuell cell to create ions?

A

Electrodes

193
Q

SC16a - What process do fuel cells mimick?

A

Photosynthesis

194
Q

SC16a - Explain how hydrogen atoms provide electricity in a fuel cell.

A
  • They hydrgoen fuel enters the fuel cell.
  • Here it reaches an electrode and becomes a hydrogen ion losing its electron.
  • The electrons move through the circuit providing a current in the circuit.
  • The hydrogen ion passes through a water membrane to meet back with an electron and react with
  • Oxygen atoms to form water.
195
Q

SC16a - What are the pros and cons of hydrogen-oygen fuel cells being used in cars?

A

Pros:

  • Quiter and need less maintenance
  • The cell itself doesn’t release greenhouse gases

Cons:

  • The production of hydrogen may release greenhouse gases and also use up fossil fuels.
  • Hydrogen needs to be stored carefully as it can explode

Koky chem (24 decks)

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