Some high-performance alloys use magnesium as a lightweight structural component.
Magnesium reacts with oxygen when heated:
magnesium+oxygen→magnesium oxide \text{magnesium} + \text{oxygen} \rightarrow \text{magnesium oxide} magnesium+oxygen→magnesium oxideA chemist calculates that 1.20 g of magnesium reacts completely with oxygen to form 2.00 g of magnesium oxide.
A student heats 1.20 g of coiled magnesium ribbon in an open crucible. Then they heat 1.20 g of magnesium powder in a separate identical crucible. After heating, the mass of the solid in each crucible is recorded.
The findings are shown in the table below.
| Form of magnesium | Colour before heating | Mass before heating in g | Time of heating in mins | Colour after heating | Mass after heating in g |
|---|---|---|---|---|---|
| Magnesium ribbon | shiny silver | 1.20 | 5 | dull grey with some white | 1.45 |
| Magnesium powder | grey | 1.20 | 10 | white | 1.88 |
Explain the observations described in the table and outline reasons why the final masses of the solids are less than the expected 2.00 g.
230 exam-style questions on Edexcel GCSE Chemistry 1.1 Formulae, equations and hazards, covering 1.1.1 Formulae, word and balanced equations, 1.1.2 Balanced ionic equations, and 1.1.3 Hazard symbols and risk in practical work. Each one has a worked solution and a mark scheme showing where the marks go.