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.