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3.3 Yield and atom economy of chemical reactions

3.3 Yield and atom economy of chemical reactions

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Question 17

This question is about reversible reactions and chemical equilibrium.

Acetylene (C2H2\text{C}_2\text{H}_2C2​H2​) is an important industrial chemical used in welding. It can be produced by the thermal cracking of methane (CH4\text{CH}_4CH4​).

The equation for the reaction is:

2CH4(g)⇌C2H2(g)+3H2(g) 2\text{CH}_4(\text{g}) \rightleftharpoons \text{C}_2\text{H}_2(\text{g}) + 3\text{H}_2(\text{g}) 2CH4​(g)⇌C2​H2​(g)+3H2​(g)
a.

Calculate the atom economy for the formation of acetylene (C2H2\text{C}_2\text{H}_2C2​H2​) in this reaction.

Relative atomic masses (ArA_{\text{r}}Ar​): H=1\text{H} = 1H=1, C=12\text{C} = 12C=12

[3]
b.

Explain the effect of increasing the pressure on the equilibrium yield of acetylene. Give your answer in terms of equilibrium.

[3]
Markscheme

3.3 Yield and atom economy of chemical reactions Questions

  1. GCSE
  2. /Chemistry
  3. /3.3 Yield and atom economy of chemical reactions

31 exam-style questions on AQA GCSE Chemistry 3.3 Yield and atom economy of chemical reactions, covering 3.3.1 Percentage yield and 3.3.2 Atom economy. Each one has a worked solution and a mark scheme showing where the marks go.

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