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3.1 Introducing chemical reactions

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Question 22

A sample of magnesium is heated in an open crucible until it has reacted completely with oxygen from the air.

2Mg+O2→2MgO 2\mathrm{Mg} + \mathrm{O_{2}} \rightarrow 2\mathrm{MgO} 2Mg+O2​→2MgO

Relative atomic mass (ArA_rAr​): Mg = 24.3 O = 16.0

What is the increase in mass when 4.86 g of magnesium reacts?

[1]
A

1.60 g

B

6.40 g

C

8.06 g

D

3.20 g

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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