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5.2 Controlling reactions

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Question 23

The equations show two stages in the pathway for a gas-phase reaction. A, B and X are symbols used for hypothetical elements.

Step 1: X2+B2→2XB\mathrm{X_{2} + B_{2} \rightarrow 2XB}X2​+B2​→2XB

Step 2: 2XB+2A→2AB+X2\mathrm{2XB + 2A \rightarrow 2AB + X_{2}}2XB+2A→2AB+X2​

When these equations are combined, which species should be written over the arrow in the overall equation?

[1]
A

X2\mathrm{X_{2}}X2​

B

B2\mathrm{B_{2}}B2​

C

XB\mathrm{XB}XB

D

AB\mathrm{AB}AB

Markscheme

5.2 Controlling reactions Questions

  1. GCSE
  2. /Chemistry
  3. /5.2 Controlling reactions

122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.

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