Edexcel IGCSEChemistryGeneral Applications8 Marks
This question is about ammonia. Ammonia can be manufactured by the Haber process. [Figure 3 shows a flow diagram of the Haber process.]
- (a)(i)Write a chemical equation for the formation of ammonia from nitrogen and hydrogen.[2]
- (a)(ii)State the name of the catalyst used in the Haber process.[1]
- (a)(iii)State the conditions of temperature and pressure used in the Haber process.[2]
- (b)Figure 3 shows the industrial process for the manufacture of ammonia. Suggest why the unreacted nitrogen and hydrogen are recycled.[1]
- (c)(i)Ammonia is used to make nitric acid. Nitric acid is a strong acid. Describe how universal indicator can be used to show that nitric acid is a strong acid.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- M1 for (a)(i) N₂ + 3H₂ ⇌ 2NH₃
- A1 for (a)(i) correct balancing (Allow multiples)
- B1 for (a)(ii) iron / Fe
- M1 for (a)(iii) temperature 400 - 450 °C
- A1 for (a)(iii) pressure 200 atm / 20 MPa (Must have units)
- B1 for (b) (to increase) yield / production / to make more ammonia / makes the process more efficient / economical / cost effective / less waste
- M1 for (c)(i) add universal indicator / UI
- A1 for (c)(i) colour red / orange / yellow (Accept pH 1-3 for A1)
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