Chemistry Paper 2 Revision

Triple Science (HT)Answer Booklet

Chemistry Revision: Rates of reaction

Key KnowledgeTWO equations for calculating rate of reaction:

Mean R of R = quantity of reactant usedTime taken

Mean R of R = quantity of product formedTime taken

Units for rate of reaction:(a) Cm3/s(b) g/s(c) mol/s

4 factors that affect rate of reaction:1) Catalyst2) Temperature3) Concentration4) Surface area5) Pressure (in gases)

Define: Activation energy: Minimum amount of energy that particles must have to react

Catalyst: provide a different pathway for a reaction that has a lower activation energy. Is not used up in the reaction.

According to collision theory, particles must collide with sufficient energy to react.

Draw a reaction profile for a reaction with and without a catalyst.

Mastery Matrix PointsCalculate the mean rate of reaction Recall the units for mass (g), volume (cm3) and rate (g/s, cm3/s, mol/s)Draw tangents on curves in order to calculate rates of reactionExplain the collision theory and link to activation energyDescribe and explain factors that affect rates of reaction (concentration, pressure, surface area, catalysts and temperature)Plot and interpret graphs showing rates of reactionExplain why one reactant is used in excess in a chemical reactionDescribe what is meant by ‘a limiting reactant’RP Rates of Reaction: Investigate how changes in concentration affect the rates of reactions by measuring volume of the gas and change of colourGive examples of catalysts Draw a reaction profile for a catalysed reaction

Time (s) Volume of CO2 (cm3)

0 010 1020 1830 2440 3050 3560 3870 4080 4190 41100 41

2. a)Plot the graph to show these results. (b) Use it to calculate the rate of reaction at 15 seconds. 8cm/20s (using a tangent) = 0.4cm/s

(c) describe AND explain the pattern shown by the results. As time increases, the volume of gas increases at a decreasing rate. This is because the reactants get used up so there are less frequent collisions.

3. Describe AND explain the effect of the 4 factors on rate of reaction:(a) Concentration: As concentration increases, rate of reaction increases. This is because there are more particles so there will be more collisions between particles. This will increase the rate of reaction.(b) Temperature: As temperature increases, rate of reaction increases. This is because the particles have more kinetic energy so more collisions are successful. This will increase the rate of reaction.(c) Surface area: As surface area increases (it is broken into smaller pieces), rate of reaction increases. This is because more particles are exposed and able to collide. This leads to more collisions and therefore will increase the rate of reaction.(d) Catalyst: This provides an alternative pathway for the reaction with a lower activation energy. This means that more particles collide with sufficient energy so there are more successful collisions and therefore rate of reaction increases.

1. Calculate rate of reaction AND write the word and symbol equation in each of these scenarios:(a) Sarah is reacting calcium carbonate with hydrochloric acid. She times

how much gas is produced in 2 minutes 30 using a gas syringe. She find that 45cm3 of gas is produced in this time. 45/150= 0.30cm3/s

Calcium carbonate + hydrochloric acid -> calcium chloride + carbon dioxide + water

CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + CO2 (g) + H2O (l)

(b) Abdi is reacting copper carbonate with hydrochloric acid. He sets this up on a top pan balance. The initial mass of the two substances is 450g. After 10 minutes, the mass of the conical flask and it’s contents is 200g. 250/600= 0.417 g/s

Copper carbonate + hydrochloric acid -> copper chloride + carbon dioxide + waterCuCO3 (s) + 2HCl (aq) -> CuCl2 (aq) + CO2 (g) + H2O (l)

(c) Linda reacts 5g of magnesium with sulphuric acid. It takes 5 minutes for the magnesium to have reacted completed. Calculate the rate of reaction, giving your answer in mol/s. 0.0014mol/sMol = 5/24=0.21 0.21/300 = 0.0007 = 7 x10-4

mol/sMagnesium + sulphuric acid -> Magnesium sulphate + hydrogen Mg (s) + H2SO4 (aq) -> MgSO4 (aq) + H2 (g)

1. Use Le Chatelier's principle to predict how the changes listed will affect the following equilibrium reaction: 2HI(g) ⇆ H2(g) + I2(g) Δ9400 (endothermic)

a. What is the effect on the concentration of HI if a small amount of H2 is added? Increase the concentration of HI as the reverse reaction will be favoured to return the system to equilibrium.

b. What is the effect on the concentration of HI if the pressure of the system is increased? No effect as there are an equal number of moles on each side so the reactions will continue at the same rate.

c. What is the effect on the concentration of HI if the temperature of the system is increased? Decrease the concentration of HI as the forward reaction is endothermic so this reaction will be favoured to reduce the temperature and return the system to equilibrium.

d. What is the effect on the concentration of HI if a catalyst is added?No effect on the concentration of HI as this will increase the forward and backward rate of the experiment by the same amount.

2. Methanol (methyl alcohol) can be manufactured using the following equilibrium reaction. Predict the effect of the following changes on the equilibrium concentration of CH3OH(g).

CO(g) + 2H2(g) ⇆ CH3OH(g) + energy Δ-75

a. a decrease in temperature Forward reaction is exothermic so decrease in temperature will favour the exothermic reaction so that more energy is released, returning the system to equilibrium. This will increase the concentration of methanol produced.

b. an increase in pressure Favour the forward reaction as there are 3 moles on the left hand side and only 1 mole on the right hand side so increasing pressure will increase the concentration of methanol produced.

c. addition of H2(g) Increase concentration of methanol produced to return the system to equilibrium.

d. addition of a catalyst

Chemistry Revision: Reversible Reactions

Key Knowledge

Define:Reversible reactions:The products react to produce the original reactants

Endothermic reaction:A reaction that takes more energy in to break bonds than releases in making new bonds

Exothermic reaction:A reaction that releases more energy in making new bonds that takes in to break old bonds

Equilibrium:The forward and reverse reactions occur at exactly the same rate

Complete the word equation:Ammonium chloride ammonia + hydrogen chloride

If a reaction is endothermic in one direction, the opposite direction would be EXOTHERMIC.

For e.g.Hydrated copper sulphate (blue) anhydrous copper sulphate (white) + water

The forward reaction is endothermic, so the backward reaction is EXOTHERMIC

The 3 factors that affect equilibrium:- Concentration-Temperature-Pressure (in gases)

Mastery Matrix Points

Use the appropriate symbol to denote a reversible reactionExplain energy changes in reversible reactions (ammonium chloride and hydrated copper sulphate)Explain what is meant by the term ‘equilibrium’Explain and use Le Chatelier’s principle to make predictions about reactants and products (HT only)Explain the effect of changing concentration, pressure and temperature on equilibrium (HT only)

Chemistry Revision: MixturesKey KnowledgeMixture – two or more substances not chemical bonded.

Soluble – can dissolveInsoluble – cannot dissolveSolute – solid that dissolvesSolvent – liquid that can dissolve a solid

FiltrationUsed to separate: insoluble solids from liquidsEquipment: filter paper, funnel and conical flask.

CrystallisationUsed to separate: soluble solids from liquids.Equipment: evaporating basin, Bunsen burner, tripod, gauze.

Simple distillationUsed to separate: liquids with different boiling points or liquids from soluble solids. Equipment: round bottom flask, Bunsen burner or heater, condensing tube,

ChromatographyUsed to separate: different coloured liquids. Equipment: chromatography paper, solvent, beaker.

Fractional distillationUsed to separate: liquids with different boiling points. Equipment: fractionating column

Mastery Matrix PointsUse key terms (soluble, insoluble, solute, solvent and solution) correctly to describe a substance dissolvingExplain how to separate given mixtures (filtration, crystallisation, simple distillation, fractional distillation, chromatography)Explain the difference in difficulty of separating compounds compared to mixtures

Understanding and Explaining

1. Mixtures be separated by physical processes. Explain what a physical process is and give four examples.

A physical process does not involved chemical reactions. Examples are crystallisation, filtration, chromatography and distillation.

2. Explain why compounds cannot be separated by physical processes.

Compounds contain elements that are chemically bonded to each other. They required chemical reactions to separate them and break the bonds.

3. Describe the process of filtration using sandy water as an example.

The filter paper has small holes that allows small particles, like the water, to pass through creating the filtrate. The residue is left in the filter paper which is made up of particles that are too large to fit through the paper – in this case the sand.

4. Describe the process of crystallisation using copper sulfate solution as an example.

Copper sulfate solution is heated in an evaporating basin. The water boils and evaporates leaving behind solid copper sulfate crystals. The more gentle the evaporation, the larger the crystals will be.

5. Describe the process of paper chromatography and how you could use it to see if a food dye is pure.

Pure substances are made up of only one thing. Draw a paper line on some chromatography paper. Put a dot of the food dye on the paper line. Put the very bottom of the paper in water and allow the water to soak up the paper through the line. If there is only one dot of colouring that is left at the end, the dye was pure. If there are two or more different coloured dots produced up the paper, the dye was not pure.

6. Describe the process of distillation using an ethanol and water mixture as an example.

Heat the ethanol and water mixture up to about 70C. Ethanol boils at 70C, but water does not. The ethanol was vaporise and go into the condensing tube where it will cool and condense back in to a liquid. The water will remain in the flask.

7. Explain the difference between simple distillation and fractional distillation.

Simple distillation is used to separate out and collect one liquid, however fractional distillation involves the use of a fractionating column to collect a number of different liquids with different boiling points.

Chemistry Revision: Chemical tests & calculations

Key KnowledgeGas tests:

Gas

Description of test Positive result

Negative result

O2 Place a glowing splint in gas

Splint relights

Splint does not relight

H2 Place a burning splint in gas

Squeaky pop

No sound

produced

CO2

Shake or bubble through limwater

Limewater turns

milky (cloudy)

Limewater

remains clear

Cl2 Test with damp litmus paper

Bleached white

Remains the same

colour

Sulfates produce a Whiteprecipitate when they react with barium chloride solution (in the presence of dilute HCl catalyst).

Carbonates react with acid to produce Carbon Dioxide gas. This can be identified using Limewater.

Mastery Matrix Points Describe the gas test for carbon dioxide, hydrogen, oxygen and chlorineExplain how to use silver nitrate solution in the presence of dilute nitric acid to test for halide ions (chloride, bromide, iodide) (triple only)Explain how to use barium chloride solution in the presence of dilute hydrochloric acid to test for sulphate ions (triple only)RP Identifying Ions: Use all of the chemical tests listed above to test for the presence of different ions (testing for metal ions: flame tests, hydroxide solutions and testing for negative ions – halides, sulphate ions, and carbonates) (triple only)

Understanding and Explaining1. Write a word and symbol equation (with state

symbols) for the reaction of:(a) calcium bromide with dilute silver nitrate solution.

Calcium bromide + silver nitrate -> calcium nitrate + silver bromide

CaBr2 (aq) + 2AgNO3 (aq) -> Ca(NO3)2 (aq)+ 2AgBr (s)

(b) magnesium carbonate with sulphuric acid.Magnesium carbonate + sulphuric acid -> magnesium

sulphate + carbon dioxide + waterMgCO3 (s) + H2SO4 (aq) -> MgSO4 (aq) + CO2 (g)+ H2O

(l)

(c) Iron (II) sulphate solution and sodium hydroxide solution

Iron (II) sulphate + sodium hydroxide -> Iron (II) hydroxide + Sodium sulphate

FeSO4 (aq) + NaOH (aq) -> Fe(OH)2 (s) + Na2SO4 (aq)

2 Genesis believes that a metal is calcium. Tyler disagrees. Describe two chemical tests that Genesis could do to prove that she is correct. You should include the results that she would expect. Flame test -> colour expected would red/orangeReact with sodium hydroxide - produce a white precipitate.

3.Simone believes that a substance is Iron (II) bromide. Describe two chemical tests that she could use to prove that she is correct. You should include the results that she would expect if she is correct.React with sodium hydroxide solution – produce green precipitateReact with dilute nitric acid and then dilute silver nitrate solution – cream precipitate formed.

Metal ions (cations)Flame test are used to identify metal ions

Metal ion

Colour of flame

Metal ion

Colour of flame

Li Crimson (red)

Ca Orange-red

Na Yellow Cu Green

P Lilac

Sodium hydroxide solution can be used to identify some metal ions (cations).

Metal ion

Colour of precipitate formed

Metal ion

Colour of precipitate formed

Al White (dissolve

s in excess NaOH)

Cu (II)

Blue

Ca White Fe (II) Green

Mg White Fe (III)

Brown

Halides - Dilute silver nitrate solution (with a dilute nitric acid catalyst) react with halides (group 7) in solution to produce coloured precipitates.

Halide Colour of silver halide (precipitate

formed)Bromid

eCream

Chloride

White

Iodide Yellow

Chemistry Revision: The Earth’s Early Atmosphere

Key KnowledgeWhich gases were in our atmosphere 4.6 billion years ago when the Earth was created?

70 % of carbon dioxide10% of water vapour10% of methane10% of ammonia

The atmosphere was very similar to the current atmosphere on two other planets Mars and Venus. The majority of these gases are thought to have been produced by volcanoes.

Which gases are currently in our Earth’s atmosphere?

80% of nitrogen20 % of oxygenVery small amounts of carbon dioxide, water vapour and noble gases.

State the 4 ways that is thought to have led to a decrease in the concentration of CO2 in the atmosphere between the Early Atmosphere and today.- Sedimentation (forming sedimentary rocks)- Formation of fossil fuels- Dissolving in the oceans- Photosynthesis

The process which caused water vapour in the atmosphere to reduce was condensation. This formed the oceans on our planet.

The process which caused oxygen levels to increase was photosynthesis. This was carried out by green plants and algae.

Mastery Matrix Points Describe the composition of the atmosphere and how long this has been the caseDescribe the development from early atmosphere to present dayDraw links between the early Earth’s atmosphere and that of other planets (Mars and Venus)Evaluate different theories regarding the Earth’s early atmosphereExplain why oxygen levels increased and carbon dioxide levels decreased (linking to photosynthesis and sedimentation)

Understanding and Explaining1. Write the word and balanced symbol equation for photosynthesis.

2. Compare and contrast the composition of the current atmosphere to that of the atmosphere 4.6 billion years ago. (4 marks)

Any 4 from:- More O2 in today’s atmosphere- More N2 in today’s atmosphere- Less CO2 in today’s atmosphere- Less water vapour in today’s atmosphere- Less methane in today’s atmosphere- Less ammonia in today’s atmosphere(or the converse)

3. The current atmosphere contains significantly more oxygen than the early atmosphere. Explain why. (4 marks)2.7 billion years ago green plants and algae started to evolve 1 markThese absorb CO2 1 markAnd produce O2 1 markIn a process called photosynthesis 1 mark

4. The current atmosphere contains significantly less carbon dioxide than the early atmosphere. Explain why. (4 marks)

Some dissolved in the oceansSome was trapped during the formation of sedimentary rocksSome was absorbed during photosynthesisSome was trapped during the formation of fossil fuels

Chemistry Revision: Global warmingKey Knowledge

Name the 3 main greenhouse gases:-Carbon dioxide-Methane-Water vapour

The waves entering the atmosphere from the sun are made up of short wavelength radiation that is easily able to pass through the atmosphere. Some of this is absorbed by the surface of the Earth whilst some is reflected/emitted as long wavelength radiation. This cannot pass through the atmosphere and so more is reflected back to the earth’s surface or absorbed causing the atmosphere to increase in temperature.

Name 2 human activities that increase the amount of:

(a) Methane:- growing rice in paddy fields- farming cattle

(b) Carbon dioxide:- burning fossil fuels for transport- deforestationState 4 potential effects of global climate change- flooding- increase in lightning- melting ice caps- increase in storms/hurricanesDefine ‘carbon footprint’: Total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

State 3 ways to reduce our carbon footprint:- recycle-take public transport- use renewable energy such as wind turbines that don’t release CO2.

Mastery Matrix Points Describe the term ‘greenhouse gases’ and give three examples (water vapour, carbon dioxide and methane)Describe the ‘greenhouse effect’ linking to the wavelength of radiationDescribe the effect of human activities on the levels of greenhouse gases, recalling two that affect methane and two that affect carbon dioxideExplain how peer review evidence have linked these activities to global climate changeExplain why it is difficult to model this and how this has led to simplification, speculation and biased opinions in the mediaDescribe 4 potential effects of global climate changeDiscuss the scale, risks and environmental implication of global climate changeDescribe what is meant by the term ‘carbon footprint’Describe actions to reduce our carbon footprint and explain why these actions may have limited impact

Understanding and Explaining5. Explain why we need some greenhouse gases in our atmosphere.

To keep the planet warm enough to sustain life.

6. Use the graph to describe the average global temperature between 1860and today.

Global average temperature has generally increased between 1860 and today.1860 = 13.5⁰C and today 14.6⁰C.Increase of 1.1⁰C.It has fluctuated between this two dates.

7. Humans are said to be having an effect on the increasing global temperature. Give two reasons why humans may be to blame and two ways that humans can help to reduce their impact over the next ten years.

- Increased use of fossil fuels- Increased deforestation to clear land for farming

- Afforestation- Recycle- Use public transport instead of our own cars

Chemistry Revision: Air PollutionKey Knowledge

One of the biggest sources of atmospheric pollution is combustion of fuels.

The gases released into the atmosphere when a fuel is burned include:- carbon dioxide- water vapour- carbon monoxide- sulphur dioxide- nitrogen oxides

Solid particles of hydrocarbons released into the atmosphere are called particulates (or soot).

State 3 properties of carbon monoxide:1) toxic2) colourless3) odourless

State 2 effects of increased sulphur dioxide and nitrogen oxides being released into the atmosphere:1) acid rain2) respiratory problems

State 2 effects of increased particulates being released into the atmosphere:1) global dimming2) health problems (e.g. asthma)

To test for the presence of carbon dioxide, I would bubble the gas through limewater and it would turn cloudy.

To test for the presence of water, I would place cobalt chloride paper in it and it would turn blue to pink.

Mastery Matrix Points Describe combustion as a major source of atmospheric pollutionName gases release when fuels such as coal are burnt (carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and nitrogen oxides) and predict which of these would be produced from a given fuel compositionDescribe ‘particulates’ Describe issues arising from carbon dioxide, sulphur dioxide, nitrogen oxides and particulates

Understanding and Explaining1. Oxides of nitrogen are produced when fuels are burnt. Write a balanced symbol equation for the production of nitrogen dioxide (NO2) from nitrogen and oxygen.

N2 + 2O2 -> 2NO2

2. Coal is a fossil fuel. Coal contains the elements hydrogen, sulfur, oxygen and carbon. Name two products of burning coal that have an impact on the environment. What impact does each of the products you named have on the environment?

Sulphur dioxide – causes acid rain and respiratory problems (asthma)Carbon dioxide – causes increase in average global temperature

3. Fuels react with oxygen to produce carbon dioxide. The reaction of a fuel with oxygen can produce a different oxide of carbon. Name this different oxide of carbon and explain why it is produced.

Carbon monoxide – insufficient oxygen during combustion

4. The table to the right shows the composition of gases found in the exhaust of a car.Explain how nitrogen oxides are formed in a car’s engine.

Due to high temperature, nitrogen in the air reacts with oxygen in air to produce nitrogen Oxide and dioxide.

Chemistry Revision: Finite ResourcesKey Knowledge

Define: “Finite resource”: a resource that will run out and isn’t easily replaced

“Renewable resource”: a resource that is easily replaced

“Synthetic”: man made

“Sustainable development”: is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.

Humans use the Earth’s resources for 4 things:1) warmth2) shelter3) food 4) transport

Give two examples of synthetic materials that are used because we do not have sufficient natural resources.

- Rubber (synthetic) instead of cotton (natural)

- Nylon (synthetic) instead of cotton (natural)

Mastery Matrix Points Recalls that humans use the Earth’s resources to provide; warmth, shelter, food, transport (through timber, clothing, fuels/energy and other materials) Define what is meant by the term ‘finite resource’Define what is meant by the term ‘sustainable development’ and explain the role that chemistry plays in developing agricultural and industrial processes

Understanding and Explaining1. Coal is described as a ‘finite’ resource. Explain why.- It will run out - Would take millions of years to replenish.

2. Using manure from cows is described as a ‘sustainable’ way of farming. Explain why.- Easily replaceable- Won’t run out

3. Recycling is viewed as being more sustainable than incinerating our waste or placing it into landfill sites. Explain why recycling is better for the environment and future population than either of the alternatives.

- Uses less natural resources- Requires less space- Produces less harmful gases into the environment

4. Wind turbines are very expensive to build yet the government has agreed £274 million of funding to build more wind farms around the UK. Suggest why they have made this decision.

- Reduces amount of CO2 produced- Renewable (doesn’t rely on fossil fuels that will run out in the future)- Expensive initially but then cost of running relatively low- No chance of SO2 or NO2 being produced so won’t contribute to acid rain

5. Developments in farming have led to the use of synthetic fertilisers. State two advantages and two disadvantages of using man made fertilisers rather than using natural fertilisers like manure.

Manure: Advantages: Cheap, doesn’t add anything potentially polluting to the land, good use of what would have been a waste product that would need to be disposed of in another way.

Disadvantages: May not contain the required mineral composition, may not be able to produce sufficient to meet needs.

Chemistry Revision: Waste & waterKey Knowledge

Define ‘potable’: Water that is safe to drink (it is NOT pure water!)

What are the two steps in producing potable water from ground (rain/fresh) water?

1) Filter (to remove any solid particles)

2) sterilise (to kill any microbes)

Give three substances that can be used to sterilise water:- Oxone-Chlorine-UV light

What are the two steps taken during desalination of salty water?

1) Heat and evaporate water2) Cool water vapour and condense

to form pure water

Which 2 substances must be removed from waste water from agriculture and sewage?1) Harmful microorganisms2) Organic material

Which two substances must be removed from industrial waste water?1) Organic material2) Harmful chemicals

RP KEY KNOWLEDGE

Mastery Matrix Points Describe the properties of potable water (is safe to drink) linking to purity, salt and microbe levels Describe the different sources of drinking water in the UK and the process that it must undergo before it is potableDescribe the process of desalination (distillation or reverse osmosis)Evaluate the methods to produce potable water (linking to location and potential water supply)RP Water Purification: Analyse and purify water samples from different sources, including pH, dissolved solids and distillationExplain why large amounts of waste water are produced (urban life styles and industrial processes)Explain what needs to be removed from sewage and agricultural waste in comparison with industrial waste water Describe the 4 steps of sewage treatmentCompare the relative ease of obtaining potable water from waste, the ground and salt water

Understanding and Explaining1. Describe the 4 stages of treating sewage. (4 marks)

*screening and grit removal (to remove large iteams)*sedimentation to produce sewage sludge and effluent (allow the solids to settle as sludge)*anaerobic digestion of sewage sludge (the solid bit!) *aerobic biological treatment of effluent (the liquid bit)

2. Compare and contrast waste water from agriculture (farming) and from a factory. (2 marks)*Both contain organic matter*Only factory waste contains harmful chemicals OR only agricultural waste contains harmful microbes

3. Which method of creating potable water would be used in the lake district? Give reasons for your choice. (3 marks)*Lots of ground water (because lots of lakes) *so filter & then sterilise. *Requires less energy so cheaper method

4. Which method of creating potable water is likely to be used in Istanbul? Give reasons for your choice. (3 marks)*Not much ground water but lots of salt water (surrounded by sea!)*So evaporate and condense*Requires much more energy but no alternative due to lack of ground water.

5. Method question on RP

Chemistry Revision: Life cycle assessments

Key KnowledgeName 2 ways of extracting copper from low grade ores:

1) Phytomining

2) Bioleaching

Give 3 advantages of using these methods instead of more traditional mining methods:

1) Don’t need to dig (creating dust)

2) Don’t need to transport (using energy/creating noise)

3) Don’t have lots of waste rocks to dispose of

How can copper be removed from the metal compounds produced by these two methods?

1) Electrolysis

2) Displacement using a more reactive metal

Name the 4 stages that must be evaluated during an LCA.

1) Extracting/processing raw materials

2) Manufacturing/packing

3) Use

4) Disposal (inc. transport)

Mastery Matrix Points Explain how phytomining and bioleaching and scrap iron and electrolysis can be used to extract copper from low grade oresDescribe what is meant by the term ‘life cycle assessment’Describe the 4 stages of a life cycle assessmentExplain that water resources, energy and waste production can be easily quantified whereas pollutant effects are hard to quantifyDescribe how simplified life cycle assessments can be used in a biased manner to support advertising claims in the mediaUse data to carry out LCA for shopping bags made from plastic and paperExplain how we can reduce our use of limited resources (reduce, reuse, recycle)

Understanding and Explaining6. Describe the 3 steps to producing copper compounds using plants: (3 marks)

- Grow plants on low grade ores- Burn plants- Collect ash

7. Describe 2 steps to producing copper compounds using bacteria: (2 marks)- Allow bacteria to feed on low grade ores- Collect leachate

8. Jared tells Waeil that an LCA is not an objective process. Explain why this is the case (2 marks)- Not all aspects can be measured quantitatively (e.g. pollutant effects)- Some judgements are made qualitatively!

9. Use the information to the right to carry out a simple LCA for plastic and paper shopping bags. Use this to decide which is better for us to useand why. The number indicates the relative quantities e.g. paper bags require 4 times more water during their entire life time. (4 marks)- Any five from: (5 marks)- Similar amount of energy used- Paper far bigger water consumption- Paper far bigger green house gas emissions- Paper more solid waste produced- Paper used significantly fewer times- Paper much quicker to degrade (break down)

- Reasonable conclusion (1 mark)

Plastic PaperConsumption of non-renewable energy

1 1.1

Consumption of water

1 4

Green house gas emissions

1 3.3

Solid waste produced

1 1.7

Average number of uses

10 2

Years taken to biodegrade

25 2

C hemistry Revision: Making MaterialsClay ceramics (including bricks and pottery) are made

by:1. shaping wet clay2. heating in a furnaceThe properties of polymers depend on:1. material they are made from2. structureTwo properties of low density poly(ethene) are:1. low melting point2. not strong3. FlexibleTwo properties of high density poly(ethene) are:1. high melting point2. strong3. InflexibleDefine ‘thermosetting polymer’:Polymers that do not melt when heatedDefine ‘themosoftening polymer’:Polymers that melt when heatedMost of the glass we use is Soda - lime glass. It is made by heating the following things together:1. sand 2. sodium carbonate3. limestone

Another type of glass is called borosilicate glass which is made from sand and boron trioxide.

Composites are made from 2 materials:- matrix (or binder)- fibre (reinforcement)

Two examples of composites are:Reinforced steel (steel = reinforcement, cement = binder).Reinforced decking (thermosetting plastic = reinforcement, sawdust = binder).

Mastery Matrix Points Explain how to produce clay ceramicsDescribe what factors affect the properties of polymersCompare low density and high density poly(ethene)Compare and contrast thermosetting and thermosoftening polymers explaining the differencesExplain what ‘composites’ are and give some examplesExplain how glass is produced Compare the composition and melting points of soda-lime glass and borosilicate glassDiscuss the environmental impact of using metal, glass, building materials, clay ceramics and plastics linking to the use of these limited resources and the energy used to extract and process them.Explain ways that we can reduce this environmental impact

Understanding and Explaining10. Compare and contrast thermosetting and thermosoftening polymers. You should make reference to their

properties AND structure.Thermosetting polymers form cross-links between polymer chains. Chains in polymers can’t slide past each other easily so it is not flexible!Thermosoftening don’t form cross-links between polymer chains. Chains can untangle and slide past each other so it is a flexible material.

11. Give an advantage of using borosilicate glass and describe one object that would be made from this material based on this property. High melting point so can be used to make cooking dishes As they won’t melt.

12. Looking at the table to the right, explain which material should be chosen for each purpose:(a) Overhead wires

Aluminium – not as dense so easy to hang in the air but still a good electrical conductor.

(b) Iron is often used to make bridges in hot countries. Which property makes it appropriate for this use? Explain your answer.

Low thermal expansion which is good as otherwise bridge would get bigger and smaller when heated in the day and cooled at night.

(c) In reference to the question above (b), why is iron often used as an alloy rather than the pure metal? You must make reference to the answer given in (b) and the table of properties.

Because as a pure metal it has low tensile strength which would make it unsuitable for a bridge!13. Describe the effect that making glass has on the

environment. How could we reduce this impact?High energy requirements so releases CO2 -> increase in global temp: Use renewable energy sources to generate the electricityHigh demand on raw products Recycle glass so that less raw materials are usedLows of non-degradable waste products produced after use: Recycle glass so that less waste is produced that must be disposed of

Property Zinc Aluminium

Magnesium

Iron

Tensile strength

54 47 34 31

Density 6300 2713 1827 6920Electrical conductivity

27.7 27 11.5 17

Thermal expansion (when put under 68⁰C)

23.3mm

21.2mm 25.2mm 12.1mm

C hemistry Revision: The Haber Process

Key KnowledgeThe purpose of the Haber process is..To produce ammonia

The word equation is:Nitrogen + Hydrogen  ⇌ Ammonia

The balanced symbol equation (with state symbols) is:N2 (g) + 3H2 (g)  ⇌ 2NH3 (g)

The conditions used are:1) 200ATM2) 450°C3) Iron Catalyst

At the end of the process, the mixture is cooled. This causes the ammonia to liquefy and be collected and the nitrogen and hydrogen remain a gas so can be recycled.

Define: Equilibrium: when the forward and backward reaction occur at the same rate

Reversible reactions: a reaction where the products can react together to form the products

Which elements are found in NPK fertilisers?1) Nitrogen2) Phosphorous3) Potassium

Mastery Matrix Points State what is produced in the Haber process and explain how ammonia produced from this process is used (triple only)List the raw materials for the Haber process and where they are sourced from (triple only)Recall the conditions required for the Haber process to take place (triple only)Recall the word and symbol equation for the Haber process (triple only)Explain how the ammonia is removed and the hydrogen and nitrogen are recycled (triple only)Interpret graphs of reaction conditions for Haber process versus rate (triple only)Apply the principals of dynamic equilibrium to the Haber process (triple only)Explain how these conditions are manipulated to produce optimum quantities of the desired products (triple only)Describe what NPK fertilisers are (triple only)

Understanding and Explaining1. Use the graph to the right to determine the conditions that should be used to

produce the highest yield of ammonia.350°C and 400ATM

2. Making reference to both yield and rate of reaction, explain why these are not the conditions used.Ideal Yield = 350°C and 400ATMIdeal Rate of reaction = 550°C and 400ATMBut compromise on temperature because exothermic reaction so low temperature favours forward reaction and creates high yield but need a slightly higher temperature so that the rate of reaction is quicker. Compromise on pressure because high pressure would favour forward reaction and create a high yield but this would be expensive due to high energy costs so compromise accepted and a slightly lower pressure used.

3. Synthetic fertilisers are prepared in the lab by the reaction of an acid with an alkali. A quantity of alkali is placed in a beaker and a solution of acid is run in until the solution is neutral. The neutral solution of salt is evaporated until crystals form. These are filtered out, washed and dried. Ammonia sulphate is produced using this method. Write the method below that must be used to create Ammonia sulphate crystals.React together Ammonia (base) with sulphuric acid until the solution becomes neutral. Test wish universal indicator. Heat the solution until the water evaporates and crystals of ammonia sulphate are formed. Filter these crystals, wash them in distilled water and dry them.

4. Potassium chloride and potassium sulphate can be obtained by mining. Phosphate rock must be reacted with an acid to form fertilisers that can be used. For each of the below acids, decide on the name of the compound that would be formed.(a) Sulphuric acid (b) Nitric acid(c) Phosphoric acid

5. Calculate the percentage by mass of phosphorus in ammonium phosphate (NH4)3PO4.

 Mass of phosphorous =  1 X P = 1 X 31 = 31The total formula mass of ammonium phosphate is: = (3 X 14) + (12 X 1) + (1 X 31) + (4 X 16) = 149The percentage by mass of phosphorus is:  (31 / 149) x 100   = 20.8%

Chemistry Revision: Fractional Distillationand Cracking

Key KnowledgeWhat is the purpose of ‘fractional distillation’?Separate crude oil into its fractions that have similar chain lengths and therefore similar properties.

State the name of some of the fuels produced from the fractions made during fractional distillation…1) Petrol 2) Petroleum gases3) Diesel oil 4) Bitumen5) Kerosene

State the name of some of the products made from the fractions made during fractional distillation in the petrochemical industry…1) Solvents 2) lubricants3) Polymers 4) Detergents

State 3 properties of fractions collected at the top of the column:1) low boiling point2) volatile (vaporises easily)3) ignites easily4) flows easily

Define ‘cracking’: breaking down long hydrocarbons to produce smaller more useful molecules

Two methods of cracking are:1) Catalytic cracking2) Steam cracking

The steps used for method (Catalyic) are:Heated and then passed over a hot catalyst

The steps used for method (Steam) are:Mixed with steam and then heated to high temperature

Mastery Matrix Points Explain the process of fractional distillationName and describe the uses (fuels and feedstock for the petrochemical industry e.g. solvents, lubricants, polymers and detergents) of each of the fractions produced (petrol, diesel, kerosene, heavy fuel oil and LPG)Describe why carbon can form such a vast array of natural and synthetic compoundsExplain how the size of hydrocarbon is linked to their boiling point, viscosity and flammability Describe the combustion of hydrocarbons and write balanced symbol equationsDescribe what is meant by ‘cracking’Describe why cracking is requiredDescribe the methods and conditions used for ‘catalytic cracking’ and ‘steam cracking’Recall the uses of alkenes produced during cracking (polymers)Balance chemical equations for cracking

Understanding and Explaining1. Explain how petroleum gases are extracted from crude oil using fractional distillation. (6 marks) - Crude oil heated until it vaporises- Vapour rises up fractional distillation column- Bottom of column is hot (350⁰C) and top is cooler (85⁰C)- Vapours rise until they reach temperature that is slightly cooler than their boiling point- Condense and are collected as a liquid- Petroleum gases have a very low boiling point so travel to the top of the column as a gas and are then

collected from the pipe leaving the top of the column.

2. Compare and contrast the properties of fractions collected at the top and bottom of the column (4 marks).Fractions at top = short carbon chains, low bp, volatile, easy to ignite WHEREASFractions at bottom = long carbon chains, high bp, not very volatile, hard to ignite

3. Cracking is a really important industrial process. Explain why it is necessary. (3 marks) High supply of long chained hydrocarbons but these aren’t as useful as they are not very easy to ignite so there is a low demand for them!High demand for short chained hydrocarbons as very easy to ignite so great for use as fuels. Cracking used to break the surplus long chained hydrocarbons into short chained hydrocarbons that are more useful so that the supply can meet the demand.

4. Complete the symbol equations to predict the products of these cracking reactions. (4 marks)EXT: Complete the word equations underneath!

(a) C10H22 -> C2H4 + C8H18 (c) C4H10 -> C2H6  + C2H4Decane -> ethene + Octane Butane -> Ethane + Ethene

(b) C5H12 -> C3H8 + C2H4 (d) C4H10  -> CH4 + C3H6Pentane -> Propane + ethene Butane -> Methane + Propene

Explain what crude oil is and how it is formedDefine ‘alkanes’ and give the general formulaRecall the formulae and structures for the first 4 alkanes (methane, ethane, propane and butane)Define ‘alkenes’ and give the general formula Recall the formulae and structures for the first 4 alkenes (ethene, propene, butane, pentene)Define the terms ‘saturated’ and ‘unsaturated’ and link to alkanes and alkenesUse the bromine test to identify whether there are alkanes or alkenes presentDefine an ‘organic compound’ (triple only)Identify the functional groups of organic compounds (alkanes, alkenes, alcohols, carboxylic acids) from formulae/structural diagram (triple only)Describe the reactions and conditions between alkenes and hydrogen, water, the halogens (Cl, Br, I) and oxygen (triple only)Draw the displayed structural formulae for the products of the reactions between alkenes, hydrogen, water, halogens and oxygen (triple only)

Chemistry Revision: Organic CompoundsKey KnowledgeWhat was crude oil made from?Remains of ancient plankton and other living organisms

Define:Organic compound: A chemical compound containing carbonSaturated: contains only single bonds Unsaturated: contains at least one carbon to carbon double bond.

Alkanes and Alkenes:Homologous group

Alkane Alkene

General formula

CnH2n+2 CnH2n

Name & formula with..1 carbon Methane

CH4NA

2 carbons EthaneC2H6

EtheneC2H4

3 carbons PropaneC3H8

PropeneC3H6

4 carbons ButaneC4H10

ButeneC4H8

5 carbons PentaneC5H12

PenteneC5H10

Combustion: burning a substance in oxygen Hydrocarbon + oxygen -> water + carbon dioxide

To test whether a substance is an alkene you…Shake with bromine water which will turn colourless

Understanding and Explaining1. Draw the structural formula for:

(a) Butane (b) Propene

2. Alkenes tend to burn with smoky flames. Explain why.Tend to have incomplete combustion so produce smoky flames.

3. Ethene can react with hydrogen in an addition reaction. State the conditions used and write a symbol equation and draw the structural formula for this reaction.

Catalyst and relatively high temperature C2H4 + H2 -> C2H6 Ethene + hydrogen -> Ethane

4. Propene can react with water in an addition reaction. State the conditions used and write a symbol equation and draw the structural formula for this reaction.Catalyst C3H6 + H2O -> C3H7OH Propene + water -> Propanol

5. Butene can react with chlorine in an addition reaction. State the conditions used and write a symbol equation and draw the structural formula for this reaction.C4H8 + Cl2 -> C4H8Cl2 Butene + chlorine -> dichlorobutane

Mastery matrixDescribe the process of addition polymerisation (triple only)Represent addition polymers using structural equations (triple only)Draw diagrams to show the conversion of a monomer to a polymer and vice versa (triple only)Explain the process of condensation polymerisation (triple only)Use simple diagrams to show condensation polymerisation e.g. ethane diol and hexanedic acid reacting together (triple only)Describe the structure of amino acids (triple only)Describe how amino acids form polypeptides by condensation polymerisation (triple only)Link this to the structure of DNA and the importance of polymers in producing proteins, cellulose and starch (triple only)Name the monomers that make up DNA (nucleotides), protein (amino acids), starch (glucose) and cellulose (triple only)Describe the process of addition polymerisation (triple only)

Chemistry Revision: PolymerisationKey KnowledgeDefine polymerisation: many small molecules (monomers) join together to form very large molecules (polymers).

Define monomer: small molecules that join together to make polymers.

Type of polymerisat

ion

Addition Condensation

Reactants Monomers with C=C double

bonds

Monomers with two functional

groups

Products Long chain polymers (plastics)

Long chain polymer AND

Small molecule e.g. water

Examples Polyethene Polyester

Functional groups in a:Diol – two OHDiacid- two COOHAmino acids- NH2 and a COOH

Type of monomer that makes:DNA is: Nucleotide (Sugar, base and phosphate. Protein is: Amino acidStarch is: Simple sugarsCellulose is: simple sugars

Understanding and Explaining1) Draw the polymer that would be formed from this monomer:

2) Describe what happens in addition polymerisation. You should include the reactants and products formed in your answer. You can use a specific example to support your description.

3) Draw the products that would be formed from polymerisation of these monomers:

4) Describe what happens in condensation polymerisation. You should include the reactants and products formed in your answer. You can use the example above to support your description.

5) Use the diagram to the right to: (i) explain how you know that these are amino acids.

(ii) The type of polymerisation that has occurred and how you can tell that this is the type of polymerisation occurring.

Fl

Mastery matrixRecall the formulae and structures for the first 4 alcohols (methanol, ethanol, propanol and butanol) (triple only)Recall the main uses of these alcohols (triple only)Describe the reactions between alcohols and sodium, oxygen, water and an oxidising agent (triple only)Explain how ethanol is produced by fermentation (triple only)Write balanced symbol equations for the reactions of alcohols with oxygen (triple only)Recall formulae & structures for first 4 carboxylic acids (methanoic acid, ethanoic acid, propanoic acid & butanoic acid) (triple only)Describe the reactions between carboxylic acids and carbonates and alcohols (triple only)Describe what happens when carboxylic acids dissolve in water (triple only)Explain why carboxylic acids are weak acids in terms of ionisation and pH (triple only)Draw the structure of ethyl ethanoate (triple only)

Chemistry Revision: Organic CompoundsKey KnowledgeFunctional group of

- an alcohol? -OH- a carboxylic acid is? -COOH- An ester? -COO

No. of carbons

Alcohol formula

Alcohol name

Carboxylic acid formula

Carboxylic acid name

1 CH3OH Methanol HCOOH Methanoic acid

2 C2H5OH Ethanol CH3COOH Ethanoic acid

3 C3H7OH Propanol C2H5COOH Propanoic acid

4 C5H9OH Butanol C3H7COOH Butanoic acid

2 uses of alcohols are:1) Alcoholic drinks 2) Fuel

Alcohol can be made in two ways:1) Fermentation of glucose 2) Hydration of ethene

Alcohols burn in air. The general equation is:

Alcohol + oxygen -> water + carbon dioxide

Alcohols that are added to water form solutions with a pH of 7

Alcohols react with sodium to product hydrogen and a salt E.g.Ethanol + sodium -> hydrogen + sodium ethoxide

Alcohols react with oxygen to form a carboxylic acid. E.g. ethanol reacts with oxygen in the air to form ethanoic acid.

When a carboxylic acid reacts with a carbonate, salt , carbon dioxide and water are produced.

When ethanol reacts with ethanoic acid, ethyl ethanoate is produced. This is called an ester and has the functional group -COO. It is very sweet smelling.

Understanding and Explaining1. Write the word equation for the reaction of butanol with oxygen.

Butanol + oxygen -> Butanoic acid

2. Write the word equation for combustion of methanol.Methanol + Oxygen -> water + carbon dioxide

3. Write the word equation for the reaction of methanoic acid with sodium carbonate.Methanoic acid + sodium carbonate -> Sodium methanoate + carbon dioxide +

water

4. I have two substances. I want to test which is and alcohol and which is a carboxylic acid. Describe 3 tests I could do to identify them.

Test for flammability – alcohol will ignite, carboxylic acid won’tTest for pH – alcohol = 7, carboxylic acid = pH3-7React with a carbonate – alcohol = no reaction, carboxylic acid -> CO2 produced

5. Draw the structural formula for ethanoic acid.

6. Draw the structure for ethyl ethanoate.

7. Explain why carboxylic acids are weak acids.Only partially ionised in water so form weak acids pH 4-6.

Chemistry Revision – Rates of reaction – effect of size of marble chip (use volume of gas produced!)

Key KnowledgeBig question 1:Investigate the effect of size of a marble chip (powder, small and large) on the rate of reaction when reacting with hydrochloric acid.Define: IV: The variable you changeDV: The variable you measureCV: The variables you keep the sameRepeatable: Same person repeating the same method and getting similar results.Reproducible: Different person repeating a similar method and getting similar resultsAccurate: A value close to the true value

IV: size of marble chipDV: volume of gas produced in 2 minutesCV: mass of marble chips, volume of hydrochloric acid, temperature of hydrochloric acid, whether or not you stirred the mixture

Understanding and Explaining

Equipment:*conical flask*delivery tube*gas syringe*clamp stand*clamp*stopwatch*marble chips (powder, small and large (5g)*1.0M HCl *Measuring cylinder

Method:1. Measure 50cm3 of 1.0M HCl using a measuring cylinder and add to the conical flask.2. Weigh 5g of powdered marble chips using a top pan balance.3. Add the powdered marble chips to the conical flask.4. Add the bung, delivery tube and gas syringe to the top of the conical flask.5. Start the stop watch immediately. 6. Record the volume of gas produced every 10 seconds for 120seconds. 7. Repeat using the small and then the large marble chips.

Chemistry Revision – Rates of reaction – effect of concentration (DIFFERENT TO THE PRACTICAL ON THE SHEET YOU HAVE BEEN GIVEN TO LEARN!!). – use turbidity!

Key KnowledgeBig question 1:Investigate the effect of concentration of hydrochloric acid on reaction time with sodium thiosulphate solution.Define: Turbidity: The degree to which water loses transparency (how cloudy it becomes)

Concentration: Mass per unit of volume in a solution in mol/dm3

IV – Concentration of sodium thiosulphateDV – Time taken for the cross to disappearCV - Concentration of acid, size of the cross, thickness of cross, whether the mixture is stirred or not.

Understanding and Explaining

Equipment:

*Sodium thiosulphate*Distilled water*1.0M HCl*Conical flask*Black cross*Stopwatch*10ml and 50ml Measuring cylinderMethod:

1) Measure 10cm3 of sodium thiosulphate and add to the conical flask.2) Measure 40cm3 of distilled water and add to the conical flask.3) Put the conical flask on the black cross.4) Measure and add 10cm3 of HCl to the conical flask.5) Swirl the flask gently and start the stop clock.6) Stop the stop clock when you can no longer see the black cross.7) Record the time next to the concentration and then repeat steps 1-6 with at

least 4 more concentrations of sodium thiosulphate

Chemistry Revision – ChromatographyKey KnowledgeBig question 1:Identify the colours in a mixture of food colouring (X).

Define:Solvent: A solution which will dissolve a solute

Solute: A solid substance that dissolves in a solvent (solution)

Mixture: A mixture consists of two or more elements or compounds not chemically combined together

How do you calculate the Rf Value for a substance?Rf = distance travelled by substance Distance travelled by solvent

Understanding and Explaining

Equipment:

*Beaker

*Wooden splint

*Chromatography paper

*4 food colourings ‘A’-‘D’

*mixture of food colourings ‘U’

*5 glass capillary tubes

*paper clip

*ruler

*pencil

Method (draw a diagram to support your answer)

1) Use a ruler to draw a pencil ‘origin’ line 2cm from the bottom of the chromatography paper.2) Mark 5 pencil dots at equal intervals along this line3) Use a glass capillary tube to put each coloured dot onto a pencil dot4) Label each spot in pencil5) Pour water into the beaker to 1cm.6) Clip the chromatography paper to the wooden split with the spots at the bottom.

7) Carefully hang into the beaker. 8) Wait for the water to travel ¾ of the way up the paper.9) Remove the paper from the beaker and draw a pencil line at the top of the solvent (this is

the solvent front line).10) Hang the paper to dry it. 11) Measure the distance between the two pencil lines and then between the start line

and the middle of each spot of ink.

Chemistry Revision – Testing for ions (triple only)Key KnowledgeIdentify the ions found in a range of compounds.

Name 4 metal ions: Ca2+ K+ Na+ Li+

Cu2+

Name 3 halide ions: Fluoride, chloride, Bromide, Iodide

What is the formula for a sulphate ion?SO4

2-

What is the formulate for a carbonate ion?CO3

2-

Which equipment/chemicals are required to test for the following?

Metal ions: Flame test: chloride solutions of each metal, metal loop, Bunsen burnerHalide ions: sodium solutions, dilute nitric acid, silver nitrate solution Carbonate ions: sodium solutions, pipette, 6 test tubes, limewater, test tube rack, HCl

Sulphate ions: sodium solutions, HCl, barium chloride solution, 5 test tubes, test tube rack

Understanding and explanation:

1. How would I test if a substance “B” contained sodium ions? Include what would be the positive result.

Flame tests (Lithium)

1) Pour 1cm3 of solution B into a test tube2) Dip the loop into the solution3) Place the loop into the blue flame of the Bunsen burner. Observe the colour. 4) If the colour of the flame is Crimson (deep red). Lithium ions are present

2. How would I test to find out if substance “Z” contained carbonate ions? Include what would be the positive and negative results of this test.

1. Pour 1cm3 of solution Z into a test tube2. Pour 1cm3 of limewater into ANOTHER test tube.3. Add 1cm3 of dilute HCl to solution Z4. If bubbles are produced, collect the gas using a delivery tube and bubble through the

limewater solution. If the reaction bubbles AND If the limewater goes from colourless to cloudy then carbonate ions are present

3. How would I test to find out if substance “M” contained bromide ions? Include what would be the positive result.

1. Pour 1cm3 of solution M into a test tube2. Add a few drops of dilute nitric acid to solution M3. Add 1cm3 of silver nitrate solution to the test tube4. If a cream precipitate is formed then the solution contains Bromide ions

5. How would I test to find if a substance “H” contained sulphate ions? Include what would be the positive and negative results of this test.

1. Pour 1cm3 of solution H into a different test tubes2. Add a few drops of HCl into the test tube3. Add 1cm3 of barium chloride solution to the test tube4. If a white precipitate has formed then the solution contains sulphate ions

Chemistry Revision – Water purificationKey Knowledge

1. Calculate the mass of dissolved substances in a sample of water.

Which equipment would you use to carry out this practical?

10cm3 of each water sample, Bunsen burner, tripod, gauze, heat proof mat, clamp, clamp stand

2. Investigate the pH of a sample of rain water.

Identify one chemical that you would need to use to do this.

Universal indicator

What is one hazard associated with this chemical?Irritant, Flammable

How would you minimize the risk associated with this hazard?Flammability - Keep away from naked flamesIrritant – Avoid contact with skin, wear goggles to keep away from eyes

Understanding and explanation:

1. I have 3 different samples of water collected from 3 different places in the UK. How would I determine which is the purest (i.e. contains the least dissolved substances? (use steps and draw a diagram of your equipment).

1. Test each sample of water with universal indicator and record the pH2. Weigh an evaporating basin.3. Pour 10cm3 of one of the samples into an evaporating basin and heat using the equipment

set up below.4. Weigh the cooled evaporating basin and then calculate the mass of solids left in the basin5. Repeat this process with the other two samples6. The water sample with the lowest solid mass left in the evaporation basin will be the purest

sample

2. I want to compare the acidity of sea water, water from a lake in the Lake District and rain water. Explain how I would do this. (Use steps!!).

1. Test each sample of water with universal indicator 2. Compare the colour of the water sample to a pH colour chart3. Record the pH4. You can repeat the tests on each of the samples with a pH meter which will give a more

accurate value for the pH as it records the pH to 1 decimal place.