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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 6

Chromium is extracted from chromium(III) oxide by a reduction reaction with aluminium (the aluminothermic process).

a.

Explain why aluminium can be used to extract chromium from chromium(III) oxide.

[2]
b.

An equation for the reaction is:

Cr2O3+2Al→2Cr+Al2O3 \text{Cr}_2\text{O}_3 + 2\text{Al} \rightarrow 2\text{Cr} + \text{Al}_2\text{O}_3 Cr2​O3​+2Al→2Cr+Al2​O3​

Calculate the percentage atom economy for the reaction to produce chromium.

Relative atomic masses (ArA_rAr​):

  • Al=27.0\text{Al} = 27.0Al=27.0
  • Cr=52.0\text{Cr} = 52.0Cr=52.0

Relative formula mass (MrM_rMr​):

  • Cr2O3=152.0\text{Cr}_2\text{O}_3 = 152.0Cr2​O3​=152.0

Give your answer to 3 significant figures.

[4]
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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