oxford cambridge and rsa gcse (9–1) combined …...gcse (9–1) combined science (chemistry) a...

Turn over© OCR 2017 Practice paperDC (ST/JG) 162027/3

Oxford Cambridge and RSA

GCSE (9–1) Combined Science (Chemistry) A (Gateway Science)J250/10 Paper 10, C4–C6 and CS7 (PAGs C1–C5) (Higher Tier)

Year 11 TestTime allowed: 1 hour 10 minutes

OCR is an exempt Charity

H

INSTRUCTIONS• Use black ink. You may use an HB pencil for graphs and diagrams.• Complete the boxes above with your name, centre number and candidate number.• Answer all the questions. • Write your answer to each question in the space provided.• Additional paper may be used if required but you must clearly show your candidate

number, centre number and question number(s).

INFORMATION• The total mark for this paper is 60.• The marks for each question are shown in brackets [ ].• Quality of extended responses will be assessed in questions marked with an

asterisk (*).• This document consists of 20 pages.

Last name

First name

Candidatenumber

Centrenumber

You must have:• a ruler (cm/mm)• the Data Sheet for GCSE Combined Science A

(Chemistry)

You may use:• a scientific or graphical calculator• an HB pencil

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J250/10© OCR 2017 Practice paper

SECTION A

Answer all the questions.

You should spend a maximum of 20 minutes on this section.

1 The concentration of carbon dioxide in the atmosphere has been increasing for a number of years.

What is thought to be the main reason for this?

A Burning of more fossil fuels

B Increasing energy output from the Sun

C Increasing volcanic activity

D Higher ocean temperatures

Your answer [1]

2 Calcium carbonate reacts with hydrochloric acid to give calcium chloride, water and carbon dioxide.

Which of the following will give the fastest rate of reaction?

A 10 g of calcium carbonate chips with 100 ml of 0.2 mol/dm3 hydrochloric acid at 30 °C

B 10 g of calcium carbonate chips with 100 ml of 0.1 mol/dm3 hydrochloric acid at 40 °C

C 10 g of calcium carbonate powder with 100 ml of 0.1 mol/dm3 of hydrochloric acid at 30 °C

D 10 g of calcium carbonate powder with 100 ml of 0.2 mol/dm3 of hydrochloric acid at 40 °C

Your answer [1]

3 What happens to the reactivity of the elements as you go down Group 7 from fluorine to astatine?

A It changes but there is no pattern.

B It decreases.

C It increases.

D It remains the same.

Your answer [1]

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J250/10 Turn over© OCR 2017 Practice paper

4 Aluminium metal is extracted from its ore, bauxite, by electrolysis.

−−+ +

Graphitecathode

Steelcase

Moltenaluminium

Graphiteanode

Why is aluminium extracted using electrolysis?

A Aluminium is less reactive than iron.

B Aluminium is more reactive than carbon.

C Bauxite dissolves readily in water.

D Electrolysis does not use much energy.

Your answer [1]

5 The equation for the extraction of aluminium is:

2Al2O3 → 4Al + 3O2

What is the mass of aluminium oxide needed to produce 54 grams of aluminium metal?

Relative atomic mass aluminium = 27.0 Relative atomic mass oxygen = 16.0

A 86.0 g

B 102.0 g

C 156.0 g

D 204.0 g

Your answer [1]

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6 Which statement about the Group 1 element lithium is correct?

A It is a good electrical conductor and forms a basic oxide.

B It is a good electrical conductor and forms an acidic oxide.

C It is a poor electrical conductor and forms a basic oxide.

D It is a poor electrical conductor and forms an acidic oxide.

Your answer [1]

7 Scientists have developed catalysts for the chemical industry. This means that reactions can take place at lower temperatures.

Why is this an advantage to the manufacturer and the environment?

A It is better for the manufacturer because catalysts speed up the reactions and better for the environment because there is no carbon dioxide being emitted.

B It is better for the manufacturer because the catalyst can be reused and better for the environment because the catalysts remove greenhouse gases.

C It is more cost effective for the manufacturer because all catalysts are cheap to buy and better for the environment because the catalyst does not harm the environment.

D It is more cost effective for the manufacturer because less fuel is needed and better for the environment because there is less carbon dioxide being emitted.

Your answer [1]

8 Metals can be extracted from their ores using plants.

What is the name of this process?

A Bioleaching

B Carbon reduction

C Electrolysis

D Phytoextraction

Your answer [1]

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9 A reaction is at equilibrium.

If the rate of the forward reaction then increases, what will happen to the rate of the reverse reaction?

A Carries on at a steady rate

B Decreases until both the forward and reverse reactions are going at the same rate

C Increases until it is going at a higher rate than the forward reaction

D Increases until the rate of the reverse reaction is the same as the rate of the forward reaction

Your answer [1]

10 The long chain hydrocarbon can be cracked to form short chain hydrocarbons.

The reaction for one set of conditions is:

C16H34 → C8H18 + 2C3H6 + compound X

What is compound X?

A Ethene

B Pentene

C Propane

D Propene

Your answer [1]

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SECTION B

Answer all the questions.

11 This question is about Earth’s atmosphere billions of years ago.

ammonia,methaneammonia,methane

nitrogennitrogen

carbon dioxidecarbon dioxide

watervapourwater

vapour

oxygenoxygenH2H2HeHe

Present

Atmosphere’scontent (%)

100

75

50

25

Time (billion years)

04.6 4 3 2 1

(a) State how carbon dioxide and water vapour in the atmosphere were originally produced.

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(b) Compare the composition of the atmosphere at 3 billion years and at present.

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(c) Give two reasons why the percentage of carbon dioxide started to decrease around 3.3 billion years ago.

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

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2 ................................................................................................................................................

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(d) Suggest why the percentage of oxygen in the atmosphere has increased from about 2 billion years ago to the present day.

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12* This question is about recycling.

When fat, oil and grease are tipped down the drain they can solidify in the sewer forming a ‘fatberg’.

These fatbergs can be many tonnes and up to the size of an aeroplane. They block the sewers and it takes many days to dig them out. The waste is then taken away to a landfill site or burned.

70.6 m

Fatberg blocking sewer pipe Fatberg as long as an aeroplane

One water company reported that it clears 80 000 blockages a year, costing £1 million every month. However, fatbergs can be recycled into a usable fuel.

When cleaned, filtered and with the water removed, fatbergs can yield 25%–40% of oil. If this oil is treated with chemicals it can be made into biodiesel, a green fuel to run vehicles. At the moment, there are only a few reprocessing plants in the UK.

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Discuss the advantages and disadvantages of recycling fatbergs.

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13 Hydrogen peroxide (H2O2) is a compound that naturally decomposes to water and oxygen over time.

(a) Write a balanced symbol equation for this decomposition.

.............................................................................................................................................. [2]

(b) A student investigates the decomposition of hydrogen peroxide solution.

She decides to use manganese(IV) oxide (MnO2) as a catalyst to speed up the reaction.

(i) Explain how a catalyst can speed up a reaction.

Use ideas about activation energy in your answer.

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...................................................................................................................................... [2]

(ii) Draw two curves to complete the reaction profile for the decomposition of hydrogen peroxide with and without a catalyst.

Label the two curves.

Energy

Reactants

Products

Progress of reaction[1]

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(c) The student sets up this experiment.

Cotton wool

Conical flask

Manganese(IV) oxide

Mass balance

Hydrogen peroxidesolution

Method:

• Place a conical flask on a mass balance • Add 100 ml of hydrogen peroxide and manganese(IV) oxide as the catalyst • Put cotton wool loosely in the neck of the flask• Record the initial balance reading and start the timer• Record the balance reading every minute until the mass no longer changes.

Here are their results plotted on a graph.

0149.2

149.4

149.6

149.8

150.0

50 100 150 200 250 300

Mass balancereading(grams)

Time (seconds)

(i) Use the graph to calculate the rate of reaction at 150 seconds.

Give this rate to 2 significant figures.

Answer = ..................................... g/s [3]

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(ii) The graph shows the rate changes during the reaction.

Explain why.

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(d) The results of some of the student’s other experiments are shown on this graph.

0149.0

149.2

149.4

149.6

149.8

150.0

50 100 150 200 250

Time (seconds)

T

S

R

Mass balancereading(grams)

(i) Suggest a reason why experiment R was slower than experiment S.

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...................................................................................................................................... [1]

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(ii) The concentration of the hydrogen peroxide solution in experiment S was 0.30 mol/dm3.

Use the graph to work out the concentration of the hydrogen peroxide solution in experiment T.

Show how you got your answer.

Answer = ..................................... mol/dm3 [3]

(e) A very sensitive balance is needed because of the small changes in mass.

Suggest another experimental set up that would also measure this rate of reaction.

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14 Crude oil is a main source of hydrocarbons.

(a) The formula for propane is written C3H8.

Write the general formula of alkanes in terms of n, where n is the number of carbon atoms.

.............................................................................................................................................. [1]

(b) Fuels contain a mixture of hydrocarbons.

(i) Complete the word equation for the complete combustion of a hydrocarbon.

hydrocarbon + oxygen → ........................................ + ........................................ [1]

(ii) Finish and balance the equation for the complete combustion of hexane.

C6H14 + O2 → ........................................ + ........................................ [2]

(c) Apart from fuels, explain how modern life is dependent upon hydrocarbons and describe the problem with this dependency.

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15 When the Group 1 elements react with water, their atoms lose an electron from the outer shell. For sodium and potassium, these processes can be represented by the equations:

Na → Na+ + e−

K → K+ + e−

(a) Explain why potassium is more reactive than sodium by referring to the arrangement of electrons in their atoms.

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(b) The equation shows the reaction of sodium with water.

2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)

In an experiment, 0.184 g of sodium reacts with excess water.

Calculate the volume of hydrogen produced at room temperature and pressure.

The volume of one mole of a gas at room temperature and pressure is 24 000 cm3.

Answer = ..................................... cm3 [4]

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16 Most hydrocarbon fuels naturally contain some sulfur compounds.

When the fuel burns, the sulfur it contains is oxidised to sulfur dioxide.

(a) Describe how the emission of sulfur dioxide into the atmosphere can be harmful to the environment. Give one example to illustrate why.

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(b) Biofuels are a clean burning alternative fuel produced from domestic, renewable resources.

The diagram shows the UK biofuel production in 2016.

Biofuels

0.0 0.5 1.0 1.5 2.0 2.5(billion litres)

Ethanol Biodiesel Hydrotreated vegetable oil

(i) In 2016 the UK used 48.4 billion litres of fuel for transport purposes.

Calculate the maximum percentage that hydrotreated vegetable oil could contribute to this total.

Give your answer to 2 decimal places.

Answer = ..................................... % [2]

(ii) The UK is aiming for biofuels to make up 9.5% of transport fuels by 2020.

Estimate the volume of biofuel needed to reach this target.

State why this figure is only an estimate.

Answer = ..................................... billion litres

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...................................................................................................................................... [3]

END OF QUESTION PAPER

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