A student adds 12.40 g of solid Q to 18.60 g of liquid P in an open flask. Both substances react completely. A gas and other products form. The gas is the only substance that leaves the flask.
| Measurement | Mass in g |
|---|---|
| flask and contents before the reaction | 86.25 |
| flask and contents after the reaction | 83.60 |
Calculate the mass of the products that remain in the flask.
Show your working.
The reaction is repeated using the same masses of P and Q in a sealed container. The balance reading before the reaction is 86.25 g.
Predict the final balance reading. Explain your answer.
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.