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2.1 Purity and separating mixtures

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Question 34

The equation shows what happens when methane reacts with oxygen.

CH4+2O2→CO2+2H2O \mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O} CH4​+2O2​→CO2​+2H2​O

A student says, “The 2 in front of O2\mathrm{O_2}O2​ gives oxygen a total relative mass of 2×16.0=32.02 \times 16.0 = 32.02×16.0=32.0, so the reactants have a total relative mass of 48.0. The products have a larger total relative mass, so this equation does not conserve mass.”

ElementCHO
Relative atomic mass, ArA_rAr​12.01.016.0

Evaluate the student's statement.

[3]
Markscheme

2.1 Purity and separating mixtures Questions

  1. GCSE
  2. /Chemistry
  3. /2.1 Purity and separating mixtures

102 exam-style questions on OCR GCSE Chemistry 2.1 Purity and separating mixtures, covering 2.1.1 Pure substances and melting point data, 2.1.2 Relative formula mass and empirical formula, 2.1.3 Formulations as useful mixtures, 2.1.4 Techniques for separating mixtures, and 2.1.5 Chromatography and Rf values. Each one has a worked solution and a mark scheme showing where the marks go.

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