An aerospace engineer is analysing an unknown metal sample inside a vacuum furnace. The table below shows the specific heat capacities of several candidate materials:
| Material | Specific heat capacity (J/kg∘C\text{J/kg}^\circ\text{C}J/kg∘C) |
|---|---|
| Platinum | 130 |
| Cadmium | 260 |
| Brass | 380 |
| Zinc | 390 |
| Nickel | 440 |
| Aluminium | 900 |
The engineer heats the unknown sample from a solid to a liquid state at a constant rate.
The graph shows how the temperature of the sample varies with time during the heating process.
The engineer has a sample of mass 1.5 kg1.5\text{ kg}1.5 kg and records that it requires 292.5 kJ292.5\text{ kJ}292.5 kJ of thermal energy to raise its temperature from the lowest temperature to the highest temperature within its liquid state.
Use the graph to calculate the specific heat capacity of the substance. Suggest which material from the table it is most likely to be.
Suggest two reasons why the engineer cannot be certain of this identification.