A student heated 3.00 g3.00\text{ g}3.00 g of magnesium hydroxide to produce solid magnesium oxide and water vapour.
The reaction is:
magnesium hydroxide→magnesium oxide+water vapour \text{magnesium hydroxide} \rightarrow \text{magnesium oxide} + \text{water vapour} magnesium hydroxide→magnesium oxide+water vapourThe student weighed the contents of the test tube after each minute of heating. The results are shown in the table below:
| Total heating time (minutes) | Mass of contents of test tube (grams) |
|---|---|
| 0 | 3.00 |
| 1 | 2.65 |
| 2 | 2.38 |
| 3 | 2.19 |
| 4 | 2.10 |
| 5 | 2.07 |
| 6 | 2.07 |
Find the minimum heating time needed for all of the magnesium hydroxide to be completely decomposed.
Calculate the total mass of water vapour produced by decomposing the magnesium hydroxide.
53 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.