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chemistry paper 1 Flashcards

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1
Q

What are the chemical formulas for these:

  • chlorine
  • ammonia
  • ammonium
  • nitrate
  • sulfate
  • carbonate

6 marks

A
  • Cl2
  • NH3
  • NH4(+)
  • NO3(2-)
  • SO4(2-)
  • CO3(2-)
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2
Q

What are all the symbols for:

  • oxidising
  • Harmful
  • Environmental hazard
  • Highly flammable
  • Toxic
  • corrosive

6 marks

A

page 14

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3
Q

How has the history of the atom changed?

6 marks

A
  • 19th century - John Dalton described them as solid spheres that made diffrent elements
  • 1897 JJ thomson did experiments showing atoms were made of negative electrons “plum pudding model”
  • 1909 - rutherfore did the gold foild experiment - where he thought the positive alpha particles will all go thought the thin sheet of gold but a small amount were defected backwards
  • this led him to come up with the nuclear atom - that there was a positive nucleus with electrons and mostly empty space
  • scientists fould that if that was true the electrons should but atracted to the nucleus , collapsing, so Bohr suggested that electrons had shells with fixed energy
  • this was supported my many experiments
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4
Q

How was Mendeleev’s periodic table different to the one we have today?

5 marks

A
  • he ordered it in order of attomic mass - we order with the atomic number
  • He had to make swaps - we dont
  • There are gaps. (which he used to predict properties of unknown elements like ekasilicon and germaniun) - we dont
  • there were 7 groups - we have 8
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5
Q

what is the formula for the ionic compound of Ca(2+) and NO3(-)

1 mark

A

Ca(NO3)2

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6
Q

if Florine has 9 protons how many electrons does F- have

1 mark

A

10

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7
Q

What are the properties of ionic compounds?

4 marks

A
  • hight melting / boiling points due to strong attraction
  • takes a large amount of energy to break bonds
  • solid dont condect electricity but can when liquid/molten as ions are free to move
  • dissolves easily - ions sperate and are free to move so they can carry a charge
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8
Q

What are the advantages and limitations of the structure atomic models?

8 marks

A
  • 2D representations are simple and good at showing what atoms something contains and how they’re connected - but they dont show shape of ideas of size
  • dot and cross diagrams are useful for showing how compounds are formed and where the electrons bond / ion came from (in ionic bonds) but they dont tell you how they are aranged / the size
  • 3D models of ionic solids show the arrangement of ions - but dont show the outer layer of substance
  • 3D ball and stick model helps visualise structures in 3D and are more relistic the 2D - but they are misleading due to the big gaps where electrons would be interacting and incorrect scales / diffrent relative sizes of atoms
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9
Q

What are the properties of simple molecular substances (simple covalent)

5 marks

A
  • Held together by very strong covalent bonds
  • But has a very weak attraction between molecules.
  • You need to break the intermolecular forces to melt or boil so they have low boiling poins
  • As the molecule gets bigger, the strength of the intermolecular for forces increase.
  • They didn’t conduct electricity because they don’t contain free electrons or ions.
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10
Q

What are the properties of giant covalent structures?

4 marks

A
  • Strong covalent bonds.
  • Very high melting and boiling points
  • Don’t contain charged particles so they don’t conduct electricity
  • They aren’t soluble in water
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11
Q

what is the structure of diamond?

5 marks

A
  • A giant covalent lattice structure
  • Four strong covalent bonds
  • high melting point
  • very hard
  • doesnt conduct
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12
Q

What is the differences / simularitys between graphite and graphene?

6 marks

A

both:
- 3 colvalent bonds
- carbon atoms aranged in hexagons
- high melting point
- 1 delocalised electron so it can conduct

graphite:
- multiple sheets
- no colvalent bonds between layers
- soft and slippery

graphene:
- single atom think (2D)

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13
Q

what are fullerenes?

5 marks

A
  • Molecules of carbon shaped light closed tubes or hollow balls.
  • They are mainly arranged in hexagons, but also contain pentagons or hepagons.
  • used to cage molecules by forming its structure around another atom / molecule
  • this could be used to deliver drugs directly to cells in the body
  • they have and huge surface area making a great catalist
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14
Q

what are nanotubes?

4 marks

A
  • fullerenes
  • they conduct electricity
  • they have high tensive strength (can be stretched without much weight)
  • can be used to strenthen sports equipment so it can still be light-weight
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15
Q

What are the physical properties of metals?

5 marks

A
  • Electrostatic forces between metal ions and delocalised sea of electrons are very strong
  • Shiny solids at room temperature and arent soluble
  • They are more dense
  • Layers of atoms in pure metals can slide over each other, making it malleable.
  • Good conductor of electricity and heat
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16
Q

What is the reason for a change in mass during a reaction?

2 + 3 marks

For increase and decrease

A

increase:
- One of the reactants could be found in the air and the mass of gas can’t be measured
- When the gas reacts to form the product, the total mass will increase.

decrease:
- One of the products is a gas
- If the vessel isn’t enclosed, then the gas can escape from the reaction vessel as its formed So you can’t measure its mass
- Decreasing the total mass.

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17
Q

What’s the difference between molecular formula and empirical formula?

2 marks

A
  • molecular formula is the whole formula e.g C6H12O6
  • empirtical is the simplest ratio of the atom e.g
    CH2O

you can use each other to work out the other

e.g if you have to Mr and empirical you can do Mr / Mr of the empirical Version to get you multiplyer

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18
Q

what is a mole? what is the eequation?

3 marks

A
  • 6.02 x 10^23
  • if you have 1 mole of a substance the mass in grams will be the Mr for substance
  • mass = Mr x Mol
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19
Q

how do you work out mass from conc and vol

1 mark

A

conc x vol = mass
g dm-3 x dm-3 = g

(in most mass is on top)

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20
Q

practical

How can you use an experiment to find the mass of the products and reactants?

8 marks

A
  1. Get a crucible and heat it until its very hot (to clean and stop oil / water)
  2. Leave to cool then weigh it with the lid
  3. Add magnesium ribbon And Reweigh
  4. new mass - intial mass = mass of magnesium
  5. Heat crucible containing the magnesium and put on the lid to stop any bits from escaping, but leave a small gap to allow oxygen to enter.
  6. Heat for 10 minutes until the magnesium ribbon has turned white.
  7. Allow it to cool and weigh the with the lid and its contents.
  8. new mass - intial mass = mass of magnesium oxide
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21
Q

how you you work out the empirical formula from the masses of 2 elements

2 marks

A
  1. use mass = Mr x mol to work out moles
  2. get the moles of both and divide it by the lowest mol to get a ratio and put it into the compound e.g CaCl2 if it was 1:2
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22
Q

How can you work out the mass of product from the mass of the reactant?

5 marks

A
  1. Write the balanced equation
  2. Work out the Mr
  3. Work out the moles from the substance you know the mass of
  4. Find the ratio between the 2 substances to get moles of other substance
  5. moles x Mr = mass

Al + O2 -> Al2O3
135g of Al
need to find mass of Al2O3

balence = 4Al + 3O2 -> 2Al2O3
Mr Al = 27 —- Mr Al3O3 = 102
135 / 27 = 5 moles of Al
4Al : 2Al2O3 = 2:1
moles of Al2O3 = 2.5
2.5 x 102 = 255g

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23
Q

How do you account to what is a limiting reactant?

6 marks

calculate

A
  • youll be given the mass of each
  • work out the Mr
  • mass / Mr = mole for each
  • divide of by the lowest (e,g, if you had 0.1 and 0.05 you would divide both by 0,05 to get 2 and 1)
  • the lower one is the limiting
  • so the other one is in excess
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24
Q

What are the properties of solids?

4 marks

A
  • Strong forces hold them in fixed position in regular lattice arrangement.
  • fixed shape
  • Small amount of energy
  • They Vibrate the more hotter they get.
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25
Q

What are the properties of liquids?

4 marks

A
  • There was a smooth force, so particles are free to move. But tend to stick together.
  • They don’t keep shape But they keep volume
  • More energy than solid, but less than gas.
  • They have constant random mission
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26
Q

What are the properties of gases?

4 marks

A
  • no attraction so they are free to move and travel in straight lines unless they collide.
  • Don’t keep shape or volume And fills any container.
  • It has the most energy out of solid and liquids
  • Constantly moves in random motion, the hotter the faster.
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27
Q

what is it called when a solid goes to a gas?

A

subliming

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28
Q

How can you test for pure substances?

5 marks

A
  • Every element has a specific boiling and melting point
  • You can test the purity by comparing the actual melting point to the expected value.
  • If substance is a mixture (impure), it will gradually melt here at a range of temperatures
  • If it has a sharp exact melting/boiling point, it is pure
  • To do this, you can use melting point apparatus to heat up a small sample.
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29
Q

Practical

How would you carry out simple distillation?

5 marks

A
  1. Pour sample of seawater in distalation flask
  2. connect condenser to a cold tap and run cold water through
  3. heat the flask until substance with the lowest boiling point evaporates. (water at 100)
  4. The vapour passes into condenser where it goes and condenses and flows into a beaker where it’s collected.
  5. you end up with just salt in the left and water in the right

only works at VERY diffrent boiling points

pic on page 37

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30
Q

How would you carry out fractional distillation to a separate mixtures of a liquid?

5 marks

A
  1. Put mixture in the flask attached to a fractionating column and condenser
  2. Heat the different liquids as they are different boiling points and evaporate at different temperatures.
  3. Lowest boiling point will evaporate first when thermometer matches boiling point of liquid and it will go to top of column
  4. Higher boiling points may start to evaporate to but the column is cooler towards the top, so they condense before they get to the top
  5. When the first liquid has been collected, the temperature is raised, so the next substance can reach the top.

pic on page 37

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31
Q

How would you carry out filtration?

3 marks

and when can you do it

A
  • If the product of the reaction is an insoluble solid, you can use filtration to separate it from liquid.
  • It can be used in purification.
  • He put filter paper into a funnel and pour your mixture into it, the liquid parts of the mixture will run through the paper and leave behind the solid.
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32
Q

How would you carry out crystallisation to separate soluble solids from a solution?

A
  1. Pour solution into evaporating dish and heat so some water evaporates - concentating the solution
  2. Once crystal start to form. Remove the dish from the heat.
  3. I will start to become insoluble in the cold, Highly concentrated solution
  4. filter the crystals out of the solution and leave them in a warm place to dry.
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33
Q

what purification method do you use for each?

4 marks

A
  • seporating a liquid with very diffrent boling points for other thing - simple distillation
  • sepotating a insoluble solid from liquid - filtration
  • seporating solutions with close boiling points - fractional distillation
  • seporating soluble solid from solution - crystallisation
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34
Q

What is mobile and stationary phase in chromatography?

5 marks

and hows it affected

A
  • moblie -> Where the molecules can move - it is a liquid or gas
  • stationary -> molecules cant move - soild / thick liquid
  • mixtures seporate between phases as they take diffrent ammounts of time switching
  • the speed a chemical moves between depends how distribute it is
  • it depends how soluble they are in solvent and how attracted it is to stationary phase
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35
Q

practical

How would you carry out paper chromatography?

7 marks

A
  • Use pencil to draw a line near the bottom of the paper
  • Put a spot of mixture you want to be separated, on the line
  • Put a solvent into a beaker and dip the bottom of the paper in solvent
  • Use watch glass to stop evaporation.
  • When chemicals of mixture dissolve in solvent They will both move up the paper.
  • You see the different chemicals separate out forming spots at different places.
  • remove the paper from beaker. before it reaches the top and mark the distance of solvent moved.
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36
Q

how do you calculate Rf value?

4 marks

A
  • if clourless use locating agent
  • calc distance traved by solute - base line to centre spot
  • calc distance traved by solvent

distance traved by solute / distance traved by solvent = Rf (0< Rf < 1)

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37
Q

what does it mean if they have the same Rf?

2 marks

A
  • likely to be the same mixture
  • also could use standard reference maturials (SRMs) to identify its components
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38
Q

practical

How could you combine chromatography and simple distillation to analyse the composition of an ink?

5 marks

A
  1. Ink is a mixture of different dyes dissolved in a solvent.
  2. You can do simple distillation to evaporate off the solvent and collect it if ink is the lowest boiling point.
  3. The thermometer will read the boiling point - if it is the same as another substances (e.g. 100 for water) it will likely be that
  4. Then do paper chromatography of a sample of ink to separate the dyes in the ink so you can see how many there are.
  5. Then compare the rfi use and reference them to see what dyes are in the ink.
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39
Q

What are the 3 water sources in the UK?

3 marks

A
  • Surface water - lakes rivers and reservoirs
  • The groundwater from aquifiers (underground rock) 70%
  • Waste water - contaminated by a human processes. (by industry)
40
Q

How is water purified in water treatment plants?

3 marks

A
  1. Filtration - A wire mesh takes out large twigs and then gravel and sand filters out any solid bits.
  2. Sedimentation - iron/aluminium sulfate is added causing fine particals clump together at the bottom.
  3. Chlorination - chlorine gas is bubbled through killing any harmful bacteria/microbes
41
Q

Why must chemical analysis be pure?

2 marks

A
  • Deionised water hasnt got ions that are present in normal tap water
  • Although in small amounts they are homeless, it could give false results in your experiment.
42
Q

How would you investigate the neutralisation reaction between a base and an acid?

5 marks

In this example, calcium oxide (base) and dilute hydrochloric acid.

A
  1. Measure out a set volume of dilute hydrochloric acid into a comical flask using pipette.
  2. Measure a fixed mass of calcium oxide and add it to the hydrochloric acid.
  3. Wait, for the base to completely react and then record the pH of the solution with a pH probe
  4. Repeat until all of acid has been reacted Which you will see when you get unreacted calcium oxide at the bottom.
  5. You can plot a graph to see how ph changes with the mass or the base added.

page 43

43
Q

what is the ionic equation on a neutralisation reaction

1 mark

A

H(+)(ag) + OH(-)(ag) -> H2O(l)

44
Q

What is the stronger acid and why?

  1. HCl
  2. CH3COOH

2 marks

A

1 = H(+) + Cl(-)
2 = H(+) + CH3COO(-)
- 1 because 50% of of it has H(+) ions where 2 only has 12.5%
- conc of a acid isnt the same as strength tho as conc talks about how much acid is there per dm3 of water

page 44

45
Q

how does concentration of an acid affect its pH?

2 marks

A
  • if the conc of H+ ions increases by a factor of 10 the pH will decrease by 1
  • if the conc of H+ ions increases by a factor of 100 the pH will decrease by 2 and so on
46
Q

What are all the acid reactions?

4 marks

A
  • Acid + metal -> salt + hydrogen
  • Acid + metal oxide -> salt + water
  • acid + metal hydroxide -> salt + water
  • acid + metal carbonate -> salt + water + cardon dioxide
47
Q

How can you test for hydrogen

2 marks

A
  • lighter to splint burns hydrogen with oxygen to form water
  • so if you hear a squeaky pop hydrogen is present
48
Q

How can you test for carbon dioxide?

2 marks

A
  • Bubble it through lime water.
  • if it goes cloudy its present
49
Q

What are the rules of solubility?

5 marks

A
  • common salts of sodium / potassium / ammonium are soluble
  • nitrates are soluble
  • common chlorides are soluble (except silver / lead ones)
  • common sulfates (except lead / barium / calcium ones)
  • common carbonates / hydroxides are not (but sodium / potassium / ammonium ones are)

https://library.cgpbooks.co.uk/digitalcontent/CER45DF/46/index.html#t=NTAsbGVmdCwxODQuOTMsMTAyLjc0LDQ0NC43Miw5NS4xNSxsZWZ0LHRvcA==

50
Q

How would you make insoluble salts?

7 marks

In this example, lead chloride.

A
  1. Add one spatula of a lead nitrate to a test tube and add water to dissolve it, then do the same with sodium chloride
  2. Put the two solutions into a small beaker and stir.
  3. Put a folded piece of filter paper into a filter funnel and. put it in a conical flask
  4. Pour the contents of the beaker into the filter.
  5. Swill out the beaker with more deionised water and put it in the filter paper
  6. Rinse the contents to make sure all the soluble sodium nitrate has been washed away.
  7. Scrape the lead chloride into a fresh filter paper and leave it to dry.
51
Q

Practical

How would you make soluble salts using an acid and an insoluble base?

5 marks

A
  • Heat the acid in a water bath in a fume cupboard to speed up the reaction. (avoid acid fumes getting in room)
  • add the base to the acid to produce a soluble salt - You should see the access solid sink to the bottom
  • filter off the access solid to get only the salt and water.
  • Heat the solution Using a burner to evaporate some water, then leave salt to crystallise
  • filter off the solide salt and leave to dry
52
Q

How can you make soluble salts using acid and alkali reactions?

6 marks

A
  • Measure out a set amount of acid into the conical flask using a pippette and add an indicator
  • Slowly add alkali to acid using a Burette until you reach the endpoint. when the acid has been neutralised and the indicator changes colour.
  • Carry out direction again without the indicator but with the same volumes, so it won’t become contaminated.
  • The remaining solution would only be salt and water
  • Evaporate off some water and leave the solution to crystallise.
  • filter off a solid and dry it And you’ll be left with pure dry salt.
53
Q

How do you set up your electrolytes if you’re using a solution?

4 marks

electrolysis (electrodes)

A
  • Clean of the surface of two insert electrodes using emery paper.
  • Try not to touch as you may transfer grease.
  • put electrodes into a beaker filled with your electrolyte.
  • Connect electrodes to power supply using crocodile clips and wires letting a current flow through.
54
Q

How do you set up your electrolytes to produce a molten ionic substance?

4 marks

+ electrodes

A
  • Put your solid ionic substance in a crucible (bowl).
  • Heat the crucible with a bunsen burner until the solid becomes molten
  • dip the clean insert electrodes into the electrolyte
  • Connect the electrodes to a power supply using wires and clips to get a current flowing through.
55
Q

What goes to The cathode and anode in electrolysis when doing molten ionic solids?

2 marks

A

positive ions -> cathode
negative ions -> anode

56
Q

When doing aqueous solutions in electrolysis, what goes to the cathode and what goes to the anode?

4 marks

A

cathode = either the positive ion or if the ion is more reactive then hydrogen H+ will form

anode = if the negative ion is in group 7 (halide) it will form otherwise O2 will form

57
Q

What will happen if you use non insert electrodes electrolysis?

6 marks

how do you find the change in mass

A
  • If you sets up the electrolysis practical, but using copper electrodes instead of insert electrodesthe results will be diffrent
  • The mass of the anode will decrease, and the mass of the cathode will increase because the copper will be transferred to the cathode
  • Needs to be left running for 30 minutes.
  • Find the difference between the masses before and after
  • Make sure the electrodes are dried before finding mass with electronic balance
  • If you increase the current, there will be a bigger difference between the masses.
58
Q

What is the order of reactivity?

12 metals

A
  1. Potassium
  2. Sodium
  3. Calcium
  4. Magnesium
  5. aluminium
  6. Carbon
  7. Zinc
  8. Iron
  9. Hydrogen
  10. copper
  11. silver
  12. gold
59
Q

How does the way metals react with acids tell us their reactivity?

4 marks

A
  • If you fill some testing tubes with dilute hydrochloric acid With a lighted split above it.
  • The more reactive that was, the faster reaction of the acid will go.
  • The more reactive the louder the sound
  • The more reactive. the more vigorous the fizz in the water
60
Q

What is the reaction with a metal and water?

2 marks

or with steam

A
  • metal + water –> metal hydroxide + hydrogen

:——————————-:

  • less reactive metal + steam –> metal oxide + hydrogen
61
Q

What is a redox reaction?

4 marks

A
  • Displacement reaction
  • When Both Reduction and oxidisation occurs.
  • When this reaction occurs, a more reactive element reacts to take the place of a less reactive element.
  • e.g (Ca + ZnSO4 –> CaSO4 + Zn)
62
Q

What is an ore?

4 marks

A
  • A rockwich contains enough metal to make it economically worthwhile, extracting the metal from it.
  • They are mainly an oxidised version of the metal.
  • Found in the Earth’s crust
  • Unwrapped in metals can. be mined straight out the ground, but need to be refined.
63
Q

How are some metals extracted by reduction with carbon?

4 marks

A
  • Metals above carbon in the reactivity series have to be extracted using electrolysis.
  • metals below Carbon in the reactivity series can be extracted by reduction using carbon.
  • e.g. ( 2Fe(2)O(3) + 3C –> 4Fe + 3CO(2)
  • Carbon can displace place the oxygen when it’s more reactive than the metal.
64
Q

Why is using electrolysis worse than extracting using carbon?

3 marks

A
  • It is more expensive because you need a large amount of electricity.
  • You also need to melt or dissolve the metal ore
  • Is much more expensive than reduction with carbon

The lower down reactivity series, the cheaper it is to extract

65
Q

What is bioleaching

3 marks

A
  • The use of bacteria to separate metals from their ores
  • The the bacteria gets energy from the bonds between the atoms of the ore, separating the metal from the ore in the process.
  • The leachate contains metal ions, which can be extracted by. electrolysis or displacement.
66
Q

What is phytoextraction?

4 marks

A
  • This involves growning plants in soil that contain metal compounds.
  • The plant can’t use or get rid of the metal, so they gradually build up in the leaves.
  • The plants can be harvested dried and burned in a furnace. And the ash produced contains the metal compound.
  • This end can be extracted by electrolysis or displacements
67
Q

What are the benefits of recycling?

6 marks

A
  • Extracting raw materials can take large amounts of energy Which brands fossil fuels contributing acid rain and climate change
  • It only needs a small fraction of energy / money then what It would need to extract.
  • There’s a finite amount of materials
  • Mine’s damaged the environment, destroying habitats
  • It reduces landfill, which pollutes surroundings
  • It creates jobs As is lots of stages of the process
68
Q

What is a life cycle assessment

1 marks

A
  • He looks at each stage of the life of a product. And works out the potential, environmental impact at each stage.
69
Q

What are the enviromental impacts at the choice of material and manufacture stage of the life cycle assessment?

7 marks ( 2 + 5)

A

choice of material:
- Metals have to mined and extracted, which uses lots of energy and cause pollution.
- Raw materials come from crude oil, which is non renewable. and requires lots of energy and makes pollution.

manufacture:
- Manufacturing products use lots of energy and resources.
- Can cause lots of pollution and harmful fumes
- Different ways of disposing of waste
- Some waste can be recycled and turned into other useful chemicals.
- Most chemicals need water And business needs to make sure they don’t put polluted water back into the environment.

70
Q

What are the environmental impacts of the product use and disposal part of the life cycle assessment?

6 marks

A

product use:
- Paint gives off toxic fumes
- Burning fuse release greenhouse gases and other harmful substances
- fertilisers can bleach into streams and rivers, causing damage to ecosystems.

disposal:
- Products are often disposed in landfill
- This can take up space and pollute water and land
- Products might be incinerated, which causes air pollution

71
Q

What is an dynamic equilibrium When talking about reversible reactions?

6 marks

A
  • As the reactants fall, the products go up Slowing down the forwards reaction as there is less concentration on that side
  • As the concentration of the products increases, the backwards reaction will speed up.
  • At an equilibrium, both reactions are still happening, but there’s no overall effect
  • This doesn’t mean that the products/reactants are equal. They could be, there could be more products or more reactants
  • dynamic equilibrium is when the forward and backward reactions are happening at the same rate. So the concentration of the eruptions and products won’t change.
  • This can only happen in a closed system
72
Q

What 3 things change the position of an equilibrium

3 marks

A
  • Temperature
  • Pressure
  • Concentration
73
Q

What is Le chatelier’s principle?

6 marks

A

temp:
- If you decrease the temperature, the equilibrium will move to the exothermic direction to produce more heat
- If you increase the temperature, the equilibrium will move to the endothermic direction to aborb more heat

pressure:
- If you increase the pressure, the equilibrium will move to the side that has fewer moles of gas to reduce the pressure.
- If you decrease the pressure, the equilibrium will move to a side with more moles of gas to increase pressure.

concentration:
- If you increase the concentration of your reactants, the equilibrium will move to the right to use up the reactants.
- If you increase the concentration of the products, the Equilibrium will move to the left to use up the products.
- same if you decrease them

If there is a change, the equilibrium will move to counteract the change

74
Q

What other properties of transition metals?

7 marks

A
  • They’re hard, strong, shiny and malleable.
  • They conduct heat and electricity
  • High melting points apart from Mercury.
  • High densitys
  • Corrosion resistant
  • Can be used as a catalyst as they speed up rate of reaction
  • They are very colourful
75
Q

How are alloys harder than pure metals?

2 marks

A
  • Pure metals are malleable because in regular arrangement the layers of ions can slide over each other.
  • If you add a different sized atom, it will be more difficult for the layers to slide over each other, making it stronger.
76
Q

Why is steel used as an alloy of iron?

3 marks

and how is it made?

A
  • Is made by adding a small amount of carbon
  • Steal is harder and stronger
  • Iron on same wore rust and corrode but steal is much less likely to rust
77
Q

What are the many alloys we use in everyday life? And why are they used?

5 marks

A
  • Bronze (copper + tin) - strong so it can be used in decorative ornaments
  • Brass (copper +zinc) more malleable so it can be used lower friction e.g. taps / door fittings
  • gold alloy copper / silver) - Normally very soft, but when combined with stronger metals it can be used to make jewellery.
  • Aluminium alloy - Its low density with the combination of other metals to make it strong give it the ability to be used to make aircrafts.
  • magnalium (Aluminium + Magnesium) - It’s much stronger lighter and corrodes less than pure aluminium So it can be used in vehicles.
78
Q

What is Corrosion?

1 mark

A

A process where something is slowly damaged or destroyed by a chemical process.

79
Q

What are the different ways to prevent rusting

4 marks

A
  • painting - Acts as a barrier I makes it colourful.
  • oiling / greasing - Used when moving parts are involved.
  • Sacrificial protection - Putting a more reactive metal over the metal you’re using?
  • Galvanaising - An example of sacrificial protection where a coat of zinc is put over an iron object So it will lose its electrons and corrode instead of the iron
  • electroplating

You can prevent rusting by coating the iron with a barrier, keeping the water and oxygen out

80
Q

What is electroplating

5 marks

and whats it good for

A
  • Coating the surface of a metal with another metal using electrolysis.
  • The cathode is objectic you going to electroplate and the anode is the bar of metal you are using to plate.
  • Your electrolyte is a solution containing the metal ion you are going to use for the plating.
  • The metal you’re pleating over doesn’t corrode easily. so it’ll be good for cutlery and cooking utensils
  • jewellery and decorative items are often electroplated with gold or silver as it improves appearance.

page 64

81
Q

Practical

How would you carry out a titration practical to find out concentrations

6 marks

Titration allows you to find out exactly how much acid is needed to neutralise a quantity of alkali. Vice versa

A
  1. Using a pipette measure outer set volume of the alkali into a flask and add a few drops of indicator. (methyl orange)
  2. Fill a burret with a known concentration of acid
  3. Use the burret to add the acid to the alkali a bit at a time. Swirl the flask regularly. one drop at a time When you think that alkali is almost neutralised
  4. The methyl Orange will turn red when enough acid has beed added
  5. Record the volume of acid use to neutralise And repeat the process a few times, making sure you get a very similar result each time, and take the mean.
  6. To get the concentration, do moles of acid added divided by volume of acid added.

mol/dm-3 or g/dm-3

82
Q

How would you calculate a percentage yield

1 mark

A

(actual / theoretical ) x 100

83
Q

What are the reasons you never get 100% yield?

3 marks

A
  • incomplete reactions - Not all the reactants are converted into products.
  • practical losses - You always lose a bit when you transfer chemicals between containers.
  • Unwanted reactions - If unexpected reactions happen, the yield of intended product goes down Due to impurities in the reactants or change or changes to the conditions.
84
Q

How do you do atom economy to find the percentage of useful products?

1 mark

A

( (total Mr of desired product) / (total Mr of all products) ) x 100

85
Q

What are the factors that affect profit from industry?

6 marks

in terms of chemistry formulas

A
  • Atom economy - Reactions with low atom economies use up the resources very quickly and create lots of wastes You have to dispose.
  • Percentage yield - The higher the yield the more profit
  • Rate of reaction - Is it going fast enough to produce the amount of products you need to make profit
  • Reversible reactions - How expensive is controlling the reaction conditions
  • energy cost
  • raw maturial cost
86
Q

What is the reaction of the haber process?

1 mark

A

N2 + 3H(2) <-> 2NH3 (+heat)

87
Q

What are the conditions of the haber process? and why?

6 marks

A
  • The higher the pressure, the better the forward direction. (more moles on the left)
  • Pressure has to be highest possible while not being too expensive. so it operates at 200 atmospheres.
  • The forwards reaction is exothermic Which means increasing the temperature is the wrong way
  • However, the lower the temperature, the lower the rate of reaction.
  • So 450 degrees is used as a Compromise. between the maximum yield and the speed of reaction. (10% in 20s > 20% in 60s)
  • an iron catalysts makes the reaction go faster, so it reaches the equilibrium faster too, while not. affecting the position of it.

200atm, 450 degrees, iron catalyst

page 68 for pic

88
Q

How would fertilisers help plants grow?

4 marks

A
  • They contain the three main essential elements, nitrogen, phosphorus and potassium.
  • plants need these as it affects their growth and life processes
  • Fertillsers supply these if they’re missing from the soil Or can just provide more - increasing the crop yield, speed and size
  • Ammonia fertfertilisers have an advantage as they control the composition of chemicals and how much is made - and can be soluble so chemicals can disolve into soil
89
Q

How do you use titration to produce ammonium sulfate?

6 marks

A
  1. Get a flask with ammonium solution and methyl orange indicator (yellow)
  2. Put a burette above put up by a clamp containing dilute sulfuric acid.
  3. Slowly add the dilute sulfuric acid from the burret into the ammonia until the yellow colour just changes red.
  4. When it changes, it means that ammonia has been neutralised. and you have ammunia sulphate solution.
  5. The ammonium Sulphate solution isn’t pure, as it has methyl orange in it, so you have to repeat with the exact same amounts of volume with no indicator.
  6. To get ammonium sulphate crystals gently evaporate the solution And until only a little bit is left. Leaved it to crystallise, then filter out the crystals and leave to dry.
90
Q

How do you work out molar volume of a gas?

1 mark

A

gas volume / moles

dm3 / mol-1

91
Q

How many dm3 does one mole of gas take up at RTP (20 degrees and 1atm)

1 mark

A

24dm3

24000cm3

92
Q

How old do you work out the volume of gas at RTP if you have the moles

1 mark

A

moles x 24

93
Q

What is a fuel cell?

2 marks

A
  • Chemical cells produce a voltage across the cell.
  • I fuel cell is a type of chemical cell that’s supplied with fuel and oxygen And using. energy from the reaction to produce electrical energy efficiently.
94
Q

How do hydrogen-oxygen fuel cells work?

3 marks

A
  • The reaction between hydrogen and oxygen releases energy.
  • This can produce a voltage without producing any pollutants.
  • 2H2 +O2 –> 2H2O
95
Q

What are the advantages of hydrogen-oxygen fuel cells?

6 marks

A
  • Very efficient (80%)
  • Electricity is generated directly from the reaction
  • Fewer places energy can be lost to heat
  • No moving parts so no loss due to friction.
  • No greenhouse gases, no nitrogen oxides, no sulphur dioxide, no carbon monoxide, only water and heat.
  • Could replace battery switch are highly toxic
96
Q

What are the disadvantages of hydrogen-oxygen fuel cells

3 marks

A
  • Hydrogen gas takes up more space to store than a liquid fuel.
  • It is very expencive and difficult to store safely
  • Is often made from hydrocarbons or electrolysis which uses electricity often made from fossil fuels.

and is explosive

Science (7 decks)

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