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2.6 Calculations involving masses

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Question 21
F

A student heats 5.00 g of calcium carbonate in an open crucible.

CaCO3(s)→CaO(s)+CO2(g)\mathrm{CaCO_{3}(s) \rightarrow CaO(s) + CO_{2}(g)}CaCO3​(s)→CaO(s)+CO2​(g)

After cooling, the solid in the crucible has a mass of 3.40 g. Relative formula masses: CaCO3=100\mathrm{CaCO_{3}} = 100CaCO3​=100, CaO=56\mathrm{CaO} = 56CaO=56.

Which conclusion is best supported by these results?

[1]
A

All the carbonate decomposed, giving off 1.60 g1.60\,\mathrm{g}1.60g of carbon dioxide

B

Some of the calcium oxide escaped from the crucible as a gas

C

The solid gained mass by reacting with oxygen from the air

D

Some of the calcium carbonate had not decomposed when weighed

Markscheme

2.6 Calculations involving masses Questions

  1. GCSE
  2. /Chemistry
  3. /2.6 Calculations involving masses

55 exam-style questions on Edexcel GCSE Chemistry 2.6 Calculations involving masses, covering 2.6.1 Relative formula mass and percentage composition, 2.6.2 Empirical and molecular formulae, 2.6.3 Conservation of mass, 2.6.4 Reacting masses and concentration in g dm⁻³, 2.6.5 The mole and the Avogadro constant, and 2.6.6 Limiting reactants and stoichiometry. Each one has a worked solution and a mark scheme showing where the marks go.

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