(2) (1) - tavistockcollegesciencemetals... · early hip replacement joints were made from stainless...

Q1. The hip joint between the femur and pelvis sometimes has to be replaced. Early hip replacement joints were made from stainless steel.

Stainless steel is an alloy of iron, chromium and nickel.

The diagram below represents the particles in stainless steel.

(a) Use the particle diagram to complete the percentages of metals in this stainless steel.

The first one has been done for you.

(2)

Element Percentage (%)

Iron, Fe 72

Chromium, Cr

Nickel, Ni

(b) Pure iron is a relatively soft, metallic element.

(i) Why is iron described as an element?

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(ii) Suggest why pure iron would not be suitable for a hip replacement joint.

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(iii) Use the particle diagram to help you to explain why stainless steel is harder than pure iron.

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(Total 6 marks)

Q2. Aluminium has many uses because of its low density, good electrical conductivity, flexibility and resistance to corrosion.

The main steps in the extraction of aluminium are shown in the flow chart.

(a) Use the information in the flow chart to suggest the benefits of recycling aluminium.

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(b) Pure aluminium is rarely used for the construction of large objects. Small amounts of other metals are usually mixed with aluminium.

Explain why.

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(Total 5 marks)

Q3. Many everyday items are made from iron.

(a) Haematite is an ore of iron. Haematite contains iron oxide, Fe2O

3.

(i) What is the meaning of the term ore?

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(ii) Iron can be produced by reacting iron oxide with carbon in a blast furnace.

What type of reaction produces the iron?

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(iii) The word equation for this reaction is:

iron oxide + carbon → iron + carbon dioxide

Complete and balance the symbol equation for this reaction.

.....Fe2O

3 + .....C → ................... + ...................

(2)

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(b) Pure iron is relatively soft and not very strong.

The iron from the blast furnace is very hard and brittle. It contains about 4% carbon and is used as cast iron.

Explain the differences in the properties of pure iron and cast iron by referring to the diagrams.

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(c) The diagram shows the way in which iron is extracted, used and recycled.

Explain why the recycling of iron is necessary for sustainable development.

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(Total 10 marks)

Q4. Copper is a widely used metal. The main ore of copper contains copper sulfide. Copper can be extracted from copper sulfide in a three stage process.

(a) In the first stage of extraction the copper sulfide is heated in air.

(i) Balance the symbol equation for the reaction.

Cu2S + ........O

2 → .........CuO + SO

2

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(ii) Explain why there would be an environmental problem if the gas from this reaction were allowed to escape into the atmosphere.

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(b) In the second stage copper oxide, CuO, is reduced using carbon.

Describe and explain what happens during this reaction.

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(c) During the third stage the copper can be purified as shown in the diagram.

(i) What is the name of the type of process used for this purification?

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(ii) Give one use of purified copper.

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(d) Copper-rich ores are running out.

New ways of extracting copper from low grade ores are being researched.

Recycling of copper may be better than extracting copper from its ores.

Explain why.

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(Total 10 marks)

Q5. (a) Aluminium is more expensive than iron. Why is aluminium and not iron used for the central core in power cables?

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(b) Many industrial processes involve the removal of minerals by quarrying.

All quarrying has some effect on the environment and on people’s lives. Make comments about the social, economic, health, safety and environmental effects of quarrying.

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(Total 7 marks)

Q6. Cassiterite is an ore of the metal tin.

(a) What is an ore?

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(b) Some metals are obtained by removing oxygen from the metal oxide.

What name do we give to this chemical reaction?

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(c) Name one metal which must be extracted from its melted ore by electrolysis rather than by using carbon.

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(Total 4 marks)

Q7. Copper metal can be extracted from a solution of copper(II) chloride.

Copper chloride is an ionic compound.

State where the copper would collect and explain your answer fully.

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Q8. The demand for iron and steel is high.

(a) Iron that is extracted from its oxide by carbon reduction in a blast furnace is called cast iron. Cast iron contains about 4% carbon. This carbon makes cast iron very brittle.

Carbon steels can be made by the following processes.

• Blowing oxygen into molten cast iron to remove most of the carbon. • Adding a calculated amount of carbon.

Sometimes different metals may also be added to the molten carbon steels.

(i) Suggest how blowing oxygen into molten cast iron removes most of the carbon.

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(ii) Why are different metals sometimes added to molten carbon steels?

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(b) The percentage of iron and steel recycled in the UK has been increasing.

The UK government has set targets for the percentage of iron and steel to be recycled. In 2006 the target was exceeded.

Suggest two reasons why the UK government wants to encourage recycling of iron and steel.

1 ..................................................................................................................................

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(Total 5 marks)

Year %iron and steel recycled

1998 25

2000 35

2002 42

2004 46

2006 57

Q9. Copper is found in the Earth’s crust as an ore containing copper sulfide. Large areas of land, where this ore was once quarried, are contaminated with low percentages of copper sulfide. Copper would be too expensive to extract from this contaminated land using the traditional method of quarrying and then heating in a furnace.

(a) The percentage of copper ore in the contaminated land is low.

(i) It would be too expensive to extract from this land by the traditional method.

Explain why.

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(ii) Extracting copper from this land by the traditional method would have a major environmental impact.

Give one reason why.

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(b) One way to extract the copper from land that contains low percentages of copper sulfide is by bioleaching. Bioleaching uses bacteria. The bacteria produce a solution of copper sulfate.

It is possible to get copper from a solution of copper sulfate using scrap iron.

(i) It is economical to use scrap iron to get copper.

Give one reason why.

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(ii) Why can iron be used to get copper from copper sulfate solution?

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(c) A new way to extract the copper from land that contains low percentages of copper sulfide is phytomining.

Phytomining uses plants. Plants are grown on this land and absorb copper compounds through their roots.

(i) Use this information to give two advantages of phytomining compared to the traditional method.

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(ii) Use this information to suggest one disadvantage of phytomining compared to the traditional method.

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(Total 7 marks)

Q10. An advert for crisps claimed that they are healthier because they are cooked in sunflower oil.

(a) A student found the following information about four oils that are used to make crisps.

One hypothesis is that oils are thought to be healthier if they are: • low in saturated fat • high in polyunsaturated fat.

Rapeseed oil Sunflower oil Olive oil Corn oil

Saturated fat (%) 6.6 12.0 14.3 14.4

Polyunsaturated fat (%) 29.3 63.3 8.2 51.3

Melting point (°C) +5 –18 –12 –15

(i) Use the table to decide which oil should be healthiest. Explain your decision by comparing this oil with other oils from the table that you think are less healthy.

Healthiest oil is .....................................................................................

Explanation ...........................................................................................

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(ii) These oils can be hardened by reacting them with hydrogen. A student said that hardening would make sunflower oil healthier. Is this student’s claim correct?

Explain your answer.

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(b) A mixture of the olive oil, water and egg yolk was shaken and left to stand. The olive oil and water do not separate.

The diagram shows a simple model of how a stable mixture of olive oil and water is produced by the addition of egg yolk.

Use this simple model to explain how the molecules in the egg yolk are able to produce a stable mixture of olive oil and water.

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(Total 7 marks)

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Q11. An advert for some crisps claims that they now contain only 30% saturated fat because they are cooked in sunflower oil. The crisp company used bromine water to compare percentage unsaturation of sunflower oil with four other vegetable oils, A, B, C and D.

(i) What is the range of percentage unsaturation for oils A, B, C and D?

Range = ................................................ % (1)

Oil

Volume of bromine water added until

the bromine colour just remains (cm3) Percentage unsaturation

(%) Test 1 Test 2 Test 3 Average

Sunflower 25.4 28.0 27.0 26.8

A 13.0 14.0 15.0 14.0 35

B 23.2 11.2 24.0 23.6 59

C 19.9 21.1 20.2 20.4 51

D 9.5 8.8 9.3 9.2 23

(ii) Describe and explain what happens to the first drops of bromine water that are added to these oils.

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(iii) The average for oil B is given as 23.6 cm3.

Explain how this average has been calculated.

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(iv) The results did not show that sunflower oil contains 30% saturated fat.

Explain why. (You will need to calculate the percentage unsaturation of sunflower oil.)

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(Total 6 marks)

Q12. Margarine is manufactured using ‘hard’ plant oils. A margarine company tested several plant oils to determine their hardness for use in its margarine.

In the test iodine solution was used to find the iodine value. The units are grams of iodine that react with 100 g of oil.

Plant oils with lower iodine values are harder and are less unsaturated.

Plant oil Melting point in °C Iodine value

Coconut 25 10

Palm 35 54

Olive –6 81

Castor –18 85

Peanut 3 93

Rapeseed –10 98

Sunflower –17 125

Soya bean –16 130

(a) Do the results in the table indicate that there is a relationship between the melting point of a plant oil and its hardness?

Explain your answer.

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(b) The company stated that some of the plant oils were brown and that this may have affected the results.

Explain why the company considered the colour of plant oils to be a problem with this test.

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(c) A consumer group stated that the test should not be carried out by the margarine company but by independent scientists.

Explain why.

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(d) The company intends to use sunflower oil to make its margarine.

Explain how the company could process the sunflower oil to make it suitable for the manufacture of margarine.

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(Total 9 marks)

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Q13. A company compared the relative ‘unsaturation’ of five oils. Bromine water was added from a burette to equal amounts of each oil until the bromine water remained orange-yellow.

The volume added was recorded.

(i) What would you see when the first few drops of bromine water are added to each oil?

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Type of oil Volume of bromine water

added in cm3

Maize 25.6

Olive 6.1

Palm 4.9

Soya Bean 29.9

Sunflower 25.1

(ii) What do these results tell you about sunflower oil compared with the other oils?

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(Total 3 marks)

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Q14. This information was taken from a label on a packet of crisps.

Saturated fats are linked to heart problems. In order to claim that their crisps are healthy, the manufacturer keeps the proportion of saturated fats low.

Main ingredients:

Potatoes, vegetable oil, Worcester sauce flavour,

colourings, flavourings, salt.

Nutritional information (per 100 g):

Energy 2040 kJ

Protein 6.5 g

Carbohydrate 55 g

of which sugars 3 g

Fat 27 g

of which saturates 9 g

unsaturates 18 g

Fibre 4.5 g

Sodium 1.2 g

(i) What type of fat contains double carbon carbon bonds?

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(ii) The colour of bromine water is orange.

What is seen when bromine water is shaken with:

an unsaturated fat ........................................................................................................

a saturated fat? ............................................................................................................ (2)

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(iii) Unsaturated vegetable oils can be hardened to make them useful as spreads. Describe how unsaturated vegetable oils are hardened.

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(Total 5 marks)

Q15. (a) The diagrams show the results of shaking a vegetable oil with the substances indicated.

(i) Give a reason for the result in Flask 1.

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(ii) Explain the result in Flask 2.

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(b) Saturated fats are linked to heart problems. Oils that are unsaturated help to prevent heart disease. A company wants to make a ‘healthy’ soft margarine.

The company tested the same volume of different vegetable oils by shaking each with three drops of iodine solution. The results are shown in the table.

Vegetable oil Time in minutes for the

colour of iodine to ‘disappear’

Olive oil 3.5

Peanut oil 3.0

Soya oil 1.5

Sunflower oil 1.0

(i) Why does iodine react with the molecules in these oils?

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(ii) Use the company results to evaluate which one appears to be the most ‘healthy’ vegetable oil to use in the soft margarine.

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(c) The ingredients of soft margarine include hydrogenated vegetable oil.

(i) Why is hydrogenated vegetable oil used in soft margarine?

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(ii) Describe how vegetable oils are hydrogenated.

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(Total 9 marks)

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M1. (a) (Chromium =) 20 1

in correct order

(Nickel =) 8 accept Chromium = 8 and Nickel = 20 for 1 mark

1

(b) (i) (because iron is made up of only) one type of atom 1

(ii) not strong ignore soft / corrosive / flexible accept it rusts / corrodes or that it could wear away accept could change shape / bend accept layers / atoms could slide (over each other)

1

(iii) has different sized atoms / particles or structure is different/distorted / disrupted

accept not in layers or not regular 1

so it is difficult for layers / atoms / particles to slip / slide (over each other) accept layers cannot slip / slide

1 [6]

M2. (a) any three from:

• resources / aluminium / ores are conserved accept converse argument

• less / no mining or less associated environmental problems eg quarrying / eyesore / dust / traffic / noise / loss of land / habitat

ignore just pollution

• less / no waste (rock) / landfill do not accept ‘wastes 50% of the ore’

• no purification / separation (of aluminium oxide)

• (aluminium extraction / production) has high energy / electricity / heat / temperature requirements

• less carbon dioxide produced accept no carbon dioxide produced ignore references to cost

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(b) statement ignore density

1

linked reason eg (pure) Al / it is weak / soft (1) as layers / rows can slide (over each other) (1) or alloy / other metals / they make it stronger / harder (1) stops layers / rows sliding over each other (1) accept disrupts the structure owtte if no other mark awarded accept to form an alloy or to change properties for 1 mark

1 [5]

M3. (a) (i) contain enough metal to make it economical / worth while to extract 1

(ii) reduction accept displacement accept redox

1

(iii) Fe + CO2

do not accept Fe2 / Fe

4

1

correct balancing accept multiples and halves

2Fe2O

3 + 3C → 4Fe + 3CO

2

allow Fe2 / Fe

4 as ecf

1

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(b) Pure Iron

(in pure metal all the atoms are the same size and) able to slip / slide over each other – (property soft)

OWTTE ignore references to molecules / particles if they say ‘move’ both times, allow one mark but ‘crack’ or ‘split’ is wrong..

1

Cast iron

(in cast iron) different sized atoms / larger atoms or structure is distorted / disrupted

OWTTE 1

so it is difficult for layers of atoms to slip / slide over each other OWTTE

1

(c) any three from:

• conserves / saves resources / metal ores

• saves energy resources (used for extraction / processing) accept cheaper / saves money

• decreases waste materials

• decreases a named pollution do not accept acid rain

3 [10]

M4. (a) (i) Cu2S + 2O

2 → 2CuO + SO

2

accept fractions and multiple 1

(ii) any two from:

• sulfur dioxide accept sulphur dioxide / sulphur oxide / SO

2

• causes acid rain ignore other comments eg global warming / ozone / global dimming / greenhouse effect

• consequence of acid rain eg kills fish / plants 2

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(b) any two from:

• heat (copper oxide with carbon)

• oxygen is removed by carbon accept copper (oxide) loses oxygen

or carbon gains oxygen accept carbon oxide

or

carbon monoxide / carbon dioxide is produced

or

carbon displaces copper accept a correct word or balanced symbol equation

• because carbon is more reactive than copper allow a correct comparison of reactivity

2

(c) (i) electrolysis accept electroplating

1

(ii) (electrical) wiring / appliances / coins / pipes / cladding for buildings / jewellery / making alloys

1

or

named alloys

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(d) any three explanations from:

for recycling

• less acid rain (pollution)

• copper reserves last longer / conserved

or

do not run out

• energy for extraction (saved)

or

less energy required

• less mining / quarrying

• less waste (copper) / electrical appliances dumped

or

less landfill

against recycling

• collection problems

• transport problems

• difficult to separate copper from appliances

• energy used to melt the collected copper ignore electrolysis / pollution ignore ideas about less machinery / plant ignore idea of cost

3 [10]

M5. (a) any two points one mark each

accept comparison between aluminium and iron

aluminium has:

• a low density accept lighter or fewer pylons

• a good conductor of electricity

• does not corrode or rust

do not accept does not react with air do not accept last longer

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OR

• iron has:

• high density

• is a less good conductor (of electricity)

• rusts or reacts with air

(b) any 5 from:

• employment of people or cost of employment

• depletion or use of resources do not accept depletion here

• cost of energy resources

• cost of machines or buildings

• pollution by noise from traffic or quarrying

• air pollution by dust or traffic fumes

• danger of traffic on roads

• damage to landscape (eyesore)

• damage to habitats of wildlife

• lowers the value of houses nearby

• subsidence or vibration can affect roads or houses

• providing raw materials do not accept danger or falling in

5 [7]

M6. (a) ideas that it is a

• compound of metal/metal oxide/combined (NOT mixed) cpd/ named cpd O2-/S2-/CO

3

2- etc

• found naturally/in rocks/in Earth’s Crust for 1 mark each

2

(b) reduction (accept smelting/refining but not electrolysis) for 1 mark

1

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(c) One example. Al or above in Reactivity Series ie Group I or II metals NOT Pb/Cu or compounds

for 1 mark 1

[4]

M7. copper collects at the negative electrode copper positive ions

each for 1 mark [2]

M8. (a) (i) reacts with carbon / C

accept burns / oxidises carbon 1

carbon dioxide / CO2 / gas is formed / given off

accept carbon monoxide / CO accept correctly balanced equation for 2 marks ignore state symbols

1

(ii) change / improve properties accept any specific property accept to make alloys / special steels ignore brittle

1

(b) any two from:

• to conserve ores / iron accept ores / iron are non-renewable / non-sustainable allow less quarrying / mining

• to prevent the use of landfills allow reduce waste

• to conserve energy / fuel accept fossil fuels are non-renewable

• to reduce carbon / carbon dioxide emissions

• to meet EU / International targets ignore costs / demand

2 [5]

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M9. (a) (i) because large amounts of energy would be needed to extract the copper

accept because it is labour-intensive to extract copper from this land accept because copper would have to be extracted from a large area of land (owtte)

1

(ii) any one from:

• produces large amounts of solid waste

• atmospheric pollution from carbon dioxide / sulfur dioxide

• more lorries / traffic 1

(b) (i) iron is cheap accept iron is much more abundant than copper

1

(ii) iron displaces copper from solutions of its salts accept iron is more reactive than copper

1

(c) (i) any two from:

• less expensive / energy to extract the small amounts of copper

• plants will remove carbon dioxide from the atmosphere as they grow

• can release energy when plants are burned 2

(ii) not continuous as it takes a long time for plants to grow accept supply not continuous as plants only harvested once / twice a year

1 [7]

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M10. (a) (i) (healthiest oil is) sunflower (oil) or rapeseed (oil)

sunflower (oil) is healthiest because it has less saturated fat than both olive (oil) and corn (oil)

or

rapeseed (oil) is healthiest because it has the lowest value of saturated fat compared with the other oils

1

sunflower (oil) is healthiest because it has the highest value of polyunsaturated fat compared with all the other oils

or

rapeseed (oil) is healthiest because it has more polyunsaturated fat than both olive (oil) and corn (oil)

1

no mark for the choice of oil accept the use of values from the table for these comparisons

(ii) no, because hydrogen adds to the unsaturated fat or no, because hydrogen reduces the number of carbon–carbon double bonds

accept no because reacting with hydrogen increases number of single bonds

1

therefore there will be less polyunsaturated fat accept therefore there will be more saturated fat

1

(b) molecules in egg yolk act as emulsifiers accept lecithin molecules act as emulsifiers

1

because molecules in egg yolk have a ‘head’ which dissolves in / attracted to water

accept because molecules in egg yolk are hydrophilic 1

because molecules in egg yolk have a ‘tail’ which dissolves in / attracted to oil

accept because molecules in egg yolk are hydrophobic 1

[7]

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M11. (i) 23 to 59

accept 36 1

(ii) decolourise or (orange to) colourless

ignore discolours / fades do not allow oil decolourises

1

(because bromine reacts with the) (carbon) double bond ignore alkenes or reference to unsaturation

1

(iii) any one from:

• an anomalous result (11.2) / Test 2

accept (= 23.6)

• 11.2 / Test 2 is ignored when averaging accept average of tests 1 and 3

1

(iv) unsaturation 67%

average was less than it should be / only 26.8 cm3

1

(this means there is) 33% saturated fat

it should have been 28.0 cm3 to give a percentage of 70%

1 [6]

M12. (a) yes (there is the general trend) ‘as the iodine value increases the melting point decreases’ or ‘as the hardness decreases the mp decreases’

accept converse statement do not accept boiling point

or no melting points are in random order / go up and down

1

one specific use of comparative data from the table either showing the trend or an anomaly

can be gained from yes or no answer ignore bp

1

(b) the iodine turns colourless 1

this would be difficult to see (if the oil was dark coloured) allow similar colour as iodine or iodine is brown

1

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(c) (consumer may think that) the company (scientists) would be biased 1

consumer more likely to trust independent scientists allow independent scientists not biased

1

(d) add (measured amount of) hydrogen accept hydrogenation

1

any two from:

• (nickel) catalyst

• hot / 60°C temperature

• hardened accept add a hard / hydrogenated fat / oil or make an emulsion

2 [9]

M13. (i) turns colourless

accept colour disappears ignore fading

1

(ii) any two from:

• unsaturated fat content / healthiness about the same / similar to maize accept about the same number of double carbon bonds as maize accept ‘a bit less’ for similar

• less unsaturated / less healthy than soya accept fewer / less double bonds than soya ignore ‘more saturated’

• more unsaturated / more healthy than olive / palm accept more double bonds than olive / palm ignore ‘less saturated’ if no other mark awarded accept sunflower oil has (about) the same result as maize oil for 1 mark ignore comments about saturated fats

2 [3]

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M14. (i) (poly)unsaturated

accept monounsaturated 1

(ii) (turns) colourless or colour disappears / decolourises

do not accept clear 1

stays the same colour / orange / no change allow yellow-orange / orange-brown / red-orange

1

(iii) (react) with hydrogen / H2 / hydrogenation 1

any one from:

• heated / 60 °C

• catalyst / nickel 1

[5]

M15. (a) (i) water and oil do not mix / are immiscible

ignore density 1

or

don’t dissolve each other ignore emulsifier alone

1

(ii) any two from:

• emulsifier

• forms an emulsion accept description of an emulsion

• holds the two components together accept stops them separating / they mix allow bonds / binds for holds

• by lowering the surface tension accept a description of how an emulsifier works for two marks eg ‘tadpole’ diagram or dispersal of oil drops

2

(b) (i) (because they contain) a double (carbon carbon) bond accept unsaturated ignore poly or mono

1

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(ii) results suggest sunflower oil is best

or

‘the one that took the least time’ 1

because (sunflower oil) has the highest amount of unsaturation / most double bonds / least saturated

ignore uses up I2 most quickly

second mark is dependent on first 1

(c) (i) any one from:

• have a higher melting point than (vegetable) oil

• are solid at (room temperature) / hardened / harder accept useful as spreads or doesn’t soak into bread ignore hard / soft(er)

1

(ii) any two from:

• hydrogen added do not accept ‘water’

• to carbon carbon double bond / to saturate

• (nickel) catalyst / temperature 60 – 150 °C wrong catalyst doesn’t get this mark ignore high / warm temperature

2 [9]

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