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3.1 Introducing chemical reactions

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Question 3

A geochemical survey records measurements for a hydrocarbon released from a rock core. The relative formula mass of the hydrocarbon is 72.0.

MeasurementValue
Mass of hydrocarbon analysed0.72 g
Mass of carbon dioxide collected after complete combustion2.20 g
Mass of water collected after complete combustion1.08 g

Relative atomic mass (ArA_rAr​): H = 1.0 C = 12.0 O = 16.0

Which molecular formula is consistent with all the measurements?

[1]
A

C5H12\mathrm{C_{5}H_{12}}C5​H12​

B

C5H6\mathrm{C_{5}H_{6}}C5​H6​

C

C6H12\mathrm{C_{6}H_{12}}C6​H12​

D

C10H24\mathrm{C_{10}H_{24}}C10​H24​

Markscheme

3.1 Introducing chemical reactions Questions

  1. GCSE
  2. /Chemistry
  3. /3.1 Introducing chemical reactions

134 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.

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