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2.6 Calculations involving masses

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Question 17

A technician has a sample of sodium carbonate, Na2CO3\mathrm{Na_{2}CO_{3}}Na2​CO3​. The relative formula mass, MrM_rMr​, of sodium carbonate is 106.

Relative atomic mass: Na = 23

The technician needs to know how much of the mass of this compound comes from sodium. The percentage by mass of an element is its total Ar A_r\,Ar​ in the formula divided by the Mr M_r\,Mr​ of the compound, multiplied by 100. Work out what proportion of the mass of Na2CO3\mathrm{Na_{2}CO_{3}}Na2​CO3​ is sodium, giving your answer as a percentage.

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2.6 Calculations involving masses Questions

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

142 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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