AQA GCSE Chemistry Chemistry Paper 2 (Higher), 2024: Question 2
8 marks · Standard Demand difficulty · Short Answer
This multi-part question covers the Haber process, catalysts, gas testing, reaction profiles, and the uses of ammonium nitrate.
Practise this questionQuestion
Question text
02 This question is about ammonia and nitric acid.
In the Haber process ammonia is produced from nitrogen and hydrogen.
Figure 1 represents the Haber process.
Figure 1
02.1 Pipe P links the condenser to the reactor.
Why is the condenser linked to the reactor?
Use Figure 1.
[1 mark]
02.2 Which metal is used as a catalyst in this reaction?
[1 mark]
Nitric acid is produced by reacting ammonia with oxygen.
The word equation for the production of nitric acid is:
ammonia + oxygen → water + nitric acid
*05* Platinum is a catalyst in this reaction.
02.3 Describe the test for oxygen gas.
Give the result if oxygen gas is present.
[2 marks]
Test
Result
Figure 2 represents the reaction profile of the catalysed reaction between ammonia
and oxygen.
Figure 2
02.4 Complete the reaction profile for the catalysed reaction in Figure 2.
You should:
• label the activation energy
• label the reactants and products, using the names of the reactants and products.
[2 marks]
02.5 How would Figure 2 be different if no catalyst was used?
[1 mark]
Tick ( ) one box.
The final energy level would be higher.
The final energy level would be lower.
The line would reach a higher peak.
The line would reach a lower peak.
02.6 Ammonia and nitric acid react to produce the salt, ammonium nitrate.
Ammonium ions and nitrate ions both contain nitrogen.
Suggest one use of ammonium nitrate.
[1 mark]
Mark scheme
Show the mark scheme
Question 2
AO /
Question Answers Extra information Mark
Spec. Ref.
02.1 to recycle (remaining) nitrogen allow to recycle unreacted 1 AO1
and hydrogen gases 4.10.4.1
allow to return nitrogen and
hydrogen to the reactor
AO /
Spec. Ref.
02.2 iron allow Fe 1 AO1
4.6.1.4
4.10.4.1
AO /
Spec. Ref.
02.3 (test) AO1
glowing splint 1 4.8.2.2
(result)
(splint) relights MP2 is dependent upon MP1– – 1 –
being awarded
AO /
Spec. Ref.
02.4 labelled vertical arrow from ignore arrow heads 1 AO2
dotted line to peak 4.6.1.4
4.10.4.1
ammonia and oxygen on left allow NH3 for ammonia 1 4.10.4.2
and allow O2 for oxygen
nitric acid and water on right allow HNO3 for nitric acid
allow H2O for water
an answer of
scores 2 marks
AO /
Spec. Ref.
02.5 the line would reach a higher 1 AO1
peak 4.6.1.4
4.10.4.1
4.10.4.2
AO /
Spec. Ref.
02.6 fertilisers allow explosives 1 AO3
allow sports injury packs 4.10.4.1
4.10.4.2
Total Question 2 8
How to answer it
Ammonia, Nitric Acid, and the Haber Process
What this question tests
This question assesses your understanding of industrial chemistry and energy changes. Key topics include:
- The Haber Process: recycling unreacted gases and identifying the catalyst.
- Chemical Tests: identifying oxygen gas.
- Reaction Profiles: labeling activation energy, reactants, and products.
- Catalysts: how they affect activation energy on a graph.
- Uses of Salts: practical applications of ammonium nitrate.
Efficiency in the Haber Process
Correct Answer
To recycle the unreacted nitrogen and hydrogen.
Key Knowledge
The Haber process is a reversible reaction. This means not all the nitrogen and hydrogen turn into ammonia on the first pass. To save money and resources, the leftover gases are sent back to the reactor.
The Haber Process Catalyst
Correct Answer
Iron (or the symbol Fe ).
Exam Technique
You must memorize the specific catalysts for key industrial processes. For the Haber Process, it is always Iron. Don't confuse this with the Platinum used in the nitric acid stage mentioned later in the question!
Testing for Oxygen Gas
Correct Answer
- Test: Use a glowing splint.
- Result: The splint relights.
Common Errors
- Confusing a glowing splint with a burning (lit) splint. A burning splint is used for the Hydrogen "squeaky pop" test.
- Writing "it explodes" or "it catches fire" instead of the specific term relights.
Labeling Reaction Profiles
How to draw the labels
To get full marks, your diagram should look like this:
- Reactants: Write "Ammonia + Oxygen" on the flat line at the start (left side).
- Products: Write "Nitric acid + Water" on the flat line at the end (right side).
- Activation Energy: Draw a vertical arrow starting from the dotted line (reactant level) up to the very top of the peak. Label this "Activation Energy".
Examiner Insight
Many students lose marks by drawing the activation energy arrow from the bottom axis. It must start from the energy level of the reactants.
The Effect of a Catalyst
Correct Answer
The line would reach a higher peak.
Key Knowledge
A catalyst provides an alternative pathway with a lower activation energy. Therefore, if you remove the catalyst, the activation energy increases, making the "hill" on the graph higher.
Uses of Ammonium Nitrate
Correct Answer
Fertilizers
Why this answer?
Ammonium nitrate (NH₄NO₃) contains nitrogen from two sources (ammonium and nitrate). Nitrogen is essential for plant growth, making this salt an ideal fertilizer.
Other accepted uses
- Explosives
- Sports injury cold packs
Topics
Chemistry · C6: The Rate and Extent of Chemical Change · C5: Energy Changes
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 2 (Higher), 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.