iron wool moist air 10 °C iron wool moist air 25 °C iron wool moist air 40 °C The table below shows results from a student testing how temperature affects t...
Question 1 Report
The table below shows results from a student testing how temperature affects the corrosion of identical iron wool pads. Fig. 1 shows the sealed flasks containing moist air. The pads were removed after 100 hours, dried, and their mass increase was measured. A mass increase shows that oxygen atoms have joined the iron.
| Temperature / °C | Mass increase of iron wool / g |
|---|---|
| 10 | 0.04 |
| 25 | 0.13 |
| 40 | 0.31 |
(a) Use Table 1 to state the mass increase at 40 °C. [1]
(b) Describe the relationship between temperature and rate of rusting. [1]
(c) Calculate the difference in mass increase between 25 °C and 10 °C. [1]
(d) Suggest why each pad was dried before its mass was measured. [1]
(e) Name the product formed when iron reacts with oxygen and water. [1]
Answer Details
- (a) At \(40\,^{\circ}\text{C}\), the mass increase is \(0.31\text{ g}\). [1]
- (b) Rusting becomes faster as temperature increases. The mass increase rises from \(0.04\text{ g}\) to \(0.31\text{ g}\) over the stated temperatures. [1]
- (c) \[0.13\text{ g}-0.04\text{ g}=0.09\text{ g}\] The difference is \(0.09\text{ g}\). [1]
- (d) Each pad is dried to remove water that would otherwise add to the measured mass. The mass increase should be due to rust, not water left on the pad. [1]
- (e) The product is rust, also called hydrated iron(III) oxide. [1]
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