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Atoms and reactions

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Question 79

Chromium can be extracted from chromium(III) oxide, Cr2O3\text{Cr}_2\text{O}_3Cr2​O3​, by reduction with aluminium:

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​

24.5 g of Cr2O3\text{Cr}_2\text{O}_3Cr2​O3​ is reacted with an excess of aluminium. The percentage yield of chromium is 72.0%.

What is the mass of chromium obtained?

(Relative atomic masses, ArA_rAr​: O=16.0\text{O} = 16.0O=16.0, Al=27.0\text{Al} = 27.0Al=27.0, Cr=52.0\text{Cr} = 52.0Cr=52.0)

A

6.03 g6.03\text{ g}6.03 g

B

8.38 g8.38\text{ g}8.38 g

C

12.1 g12.1\text{ g}12.1 g

D

16.8 g16.8\text{ g}16.8 g

Markscheme

Atoms and reactions Questions

  1. A Level
  2. /Chemistry
  3. /Atoms and reactions

199 exam-style questions on OCR A A Level Chemistry Atoms and reactions, covering Atomic structure and isotopes, Compounds, formulae and equations, Amount of substance, Acids, and Redox. Each one has a worked solution and a mark scheme showing where the marks go.

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