11 mark
Ammonia is made from nitrogen and hydrogen.
a)
The reaction between nitrogen and hydrogen is reversible.
Explain what this means.
Explain what this means.
[1]
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Improving Processes & Products (OCR Gateway GCSE Chemistry: Combined Science)
Exam Questions
48 mins18 questions1a2 marks
This question is about the extraction of metals.
a)
When iron oxide is heated with carbon, iron is made.
i)
Complete the word equation for this reaction.
iron oxide + carbon format('truetype')%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ctext%20font-family%3D%22math12bba9f4124283edd644799e0ce%22%20font-size%3D%2216%22%20text-anchor%3D%22middle%22%20x%3D%2210.5%22%20y%3D%2216%22%3E%26%23x2192%3B%3C%2Ftext%3E%3C%2Fsvg%3E)
................................... + ...................................
................................... + ...................................[1]
ii)
Iron oxide is reduced during this reaction.
Explain how you can tell that iron oxide is reduced.
[1]
1b2 marks
b)
Look at the reactivity series of some metals. Carbon is also included.
i)
Zinc is usually extracted from zinc oxide by heating zinc oxide with carbon.
Explain why. Use the reactivity series to help you.
Explain why. Use the reactivity series to help you.
[1]
ii)
Aluminium is extracted from aluminium oxide by electrolysis.
Explain why. Use the reactivity series to help you.
Explain why. Use the reactivity series to help you.
[1]
1c2 marks
c)
The table shows some information about aluminium and zinc.
| Metal | Cost of 1kg (£) | Amount in Earth’s crust (%) |
| Aluminium | 1.31 | 8.1 |
| Zinc | 2.51 | 0.0078 |
Suggest two reasons why it could be more important to recycle zinc than aluminium.
Use information from the table to help you.
1 ................................................
2 ................................................
[2]
1d
4 marks
4 marksd)
Aluminium alloys are often used to build aircraft.
A sample of an aluminium alloy contains 1.28 g of magnesium and 43.70 g of aluminium only.
Calculate the percentage of magnesium in this alloy.
A sample of an aluminium alloy contains 1.28 g of magnesium and 43.70 g of aluminium only.
Calculate the percentage of magnesium in this alloy.
Give your answer to 3 significant figures.
Percentage of magnesium = ..................................................... %
[4]
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2a1 mark
a)
Aluminium is a metal.
Aluminium is extracted from an ore called bauxite.
Electrolysis is used to extract the aluminium.
Use the reactivity series to explain why aluminium cannot be extracted from bauxite by heating the bauxite with carbon.
[1]
2b5 marks
b)
Drinks cans are often made from aluminium.
4.0 kg of bauxite makes 1.0 kg of aluminium.
285 000 kJ of energy is needed to make 1.0 kg of aluminium from bauxite.
Aluminium can be recycled.
4.0 kg of recycled aluminium makes 3.8 kg of aluminium.
14 250 kJ of energy is needed to produce 1.0 kg of aluminium from recycled aluminium.
4.0 kg of bauxite makes 1.0 kg of aluminium.
285 000 kJ of energy is needed to make 1.0 kg of aluminium from bauxite.
Aluminium can be recycled.
4.0 kg of recycled aluminium makes 3.8 kg of aluminium.
14 250 kJ of energy is needed to produce 1.0 kg of aluminium from recycled aluminium.
i)
Describe how aluminium is recycled.
[2]
ii)
Describe and explain two advantages of recycling aluminium.
Use the information in the question in your answer.
Use the information in the question in your answer.
[3]
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3a2 marks
Aluminium is extracted from its ore using electrolysis.
Copper is extracted from its ore by heating with carbon.
a)
Explain why different methods are used to extract aluminium and copper.
[2]
3b2 marks
b)
Molten aluminium oxide contains Al3+ and O2– ions.
The electrolysis of molten aluminium oxide makes aluminium and oxygen.
i)
Write the balanced half-equation for the reaction that happens at the cathode.
Use the symbol e– to represent an electron.
[1]
ii)
Solid aluminium oxide cannot be electrolysed.
Explain why.
[1]
3c2 marks
c)
Copper is also made by electrolysis of copper sulfate solution.
Look at the diagram of the apparatus used in this electrolysis.
Describe what you would see at each electrode.
At the anode: ..................................................................
At the cathode: ...............................................................
At the anode: ..................................................................
At the cathode: ...............................................................
[2]
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1a3 marks
Higher Only
a)
The conditions used to make ammonia in the Haber process are:
- a pressure of 200 atmospheres
- a temperature of 450°C.
The reaction is an exothermic reaction.
A company making ammonia increases the temperature used to 550°C.
A company making ammonia increases the temperature used to 550°C.
i)
What happens to the rate of the reaction when the temperature is increased?
[1]
ii)
The company thinks that the increase in temperature will increase the yield of ammonia.
Is the company correct? Explain your answer.
[2]
1b2 marks
Higher Only
b)
The company wants to reduce the cost of making the ammonia.
They decide to reduce the pressure used to 150 atmospheres.
Write about two disadvantages of using a lower pressure to make ammonia.
[2]
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2a2 marks
A student investigates the reactivity of four metals, A, B, C and D.
He adds a small piece of each metal to cold water.
He then adds a small piece of each metal to dilute hydrochloric acid.
Look at his results.
| Metal | Observations in water | Observations in dilute hydrochloric acid |
| A | slow bubbling | very fast bubbling |
| B | no reaction | no reaction |
| C | fast bubbling | very fast bubbling |
| D | no change | slow bubbling |
a)
Write down the order of reactivity of the four metals A, B, C and D
............................................... most reactive
................................................least reactive
[2}
2b3 marks
3 marksHigher Only
b)
Chromium metal, Cr, reacts with nickel sulfate solution, NiSO4. Solid nickel is made.
Two possible equations for this reaction are:
Equation 1 Cr + NiSO4 → CrSO4 + Ni
Equation 2 2Cr + 3NiSO4 → Cr2(SO4)3 + 3Ni
10.40 g of chromium metal reacts with excess nickel sulfate solution to make 17.61 g of nickel.
Deduce which equation, 1 or 2, represents the reaction which takes place.
Ar : Cr = 52.0, Ni = 58.7
Two possible equations for this reaction are:
Equation 1 Cr + NiSO4 → CrSO4 + Ni
Equation 2 2Cr + 3NiSO4 → Cr2(SO4)3 + 3Ni
10.40 g of chromium metal reacts with excess nickel sulfate solution to make 17.61 g of nickel.
Deduce which equation, 1 or 2, represents the reaction which takes place.
Ar : Cr = 52.0, Ni = 58.7
[3]
2c3 marks
Higher Only
c)
Bioleaching is one method used to extract copper from ores.
Reactions involving bacteria slowly convert copper sulfide to a mixture of copper sulfate solution and sulfuric acid.
Reactions involving bacteria slowly convert copper sulfide to a mixture of copper sulfate solution and sulfuric acid.
i)
Describe two advantages of extracting copper using bioleaching instead of traditional mining.
[2]
ii)
Suggest one reason why the sulfuric acid produced during bioleaching may be harmful to the environment.
[1]
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