A technician uses a sealed pouch containing two separate compartments. Breaking the seal between the compartments mixes the two solutions. They react to form only an insoluble solid and a solution.
| Stage | Contents | Mass / g |
|---|---|---|
| before mixing | solution A | 18.6 |
| before mixing | solution B | 12.4 |
| after the reaction | insoluble solid | 7.9 |
| after the reaction | solution | to be calculated |
Calculate the mass of the solution after the reaction.
Explain why the total mass of the contents remains unchanged, even though an insoluble solid forms.
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.