Some industrial coatings contain zinc protectants.
Zinc reacts with oxygen when heated:
zinc+oxygen→zinc oxide \text{zinc} + \text{oxygen} \rightarrow \text{zinc oxide} zinc+oxygen→zinc oxideA chemist calculates that 1.30 g of zinc reacts completely with oxygen to form 1.62 g of zinc oxide.
A student heats 1.30 g of zinc pieces in an open crucible. Then they heat 1.30 g of zinc 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 zinc | Colour before heating | Mass before heating in g | Time of heating in mins | Colour after heating | Mass after heating in g |
|---|---|---|---|---|---|
| Zinc pieces | shiny grey | 1.30 | 6 | dull grey with some white | 1.41 |
| Zinc powder | dull grey | 1.30 | 12 | white | 1.55 |
Explain the observations described in the table and outline reasons why the final masses of the solids are less than the expected 1.62 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.