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3.1 Introducing chemical reactions

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Question 12
F

When 10.0 g of calcium carbonate is heated until it has completely decomposed, 5.6 g of calcium oxide is left.

CaCO3→CaO+CO2 \mathrm{CaCO_{3} \rightarrow CaO + CO_{2}} CaCO3​→CaO+CO2​

A student heats 25.0 g of calcium carbonate in an open container. The student stops heating before the reaction is complete. The mass of solid left is 20.6 g.

What mass of calcium carbonate has decomposed?

[1]
A

4.4 g

B

5.6 g

C

7.9 g

D

10.0 g

Markscheme

3.1 Introducing chemical reactions Questions

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

55 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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