Study the scenario.

A scientist put a 100 g sample of zinc and a 100 g sample of lead side by side on a hotplate for exactly the same amount of time. She then measured the temperatures of the two metals with a thermometer. The lead had a higher temperature.

Explain this result.



Answer :

Let's delve into the scenario where a scientist placed 100 g samples of zinc and lead on a hotplate for the same duration and observed that the lead had a higher temperature afterward.

1. Understanding Specific Heat Capacity:
- Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit mass. It is usually measured in Joules per gram per degree Celsius (J/g°C).
- Substances with a lower specific heat capacity require less energy to increase their temperature, compared to those with higher specific heat capacity.

2. Comparing Zinc and Lead:
- Zinc has a specific heat capacity of approximately 0.39 J/g°C.
- Lead has a specific heat capacity of approximately 0.13 J/g°C.

3. Heat Applied to Both Metals:
- Since both metal samples received the same amount of heat from the hotplate, the heat energy absorbed by both would be similar over the same time period.

4. Result Analysis:
- Lead, having a lower specific heat capacity (0.13 J/g°C), requires less energy to increase its temperature compared to zinc.
- Consequently, for the same amount of heat energy applied, the temperature increase in lead will be greater than in zinc.

5. Temperature Measurement:
- After heating both samples for the same time period, the scientist measured the temperature of the metals.
- As previously noted, lead should have a higher temperature because it absorbs heat more readily (due to its lower specific heat capacity) than zinc for the same energy input.

Conclusion: The lead sample had a higher temperature compared to the zinc sample because lead requires less energy to raise its temperature. This phenomenon is attributed to the lower specific heat capacity of lead compared to zinc. Thus, for the same amount of heat provided, lead's temperature increases more than that of zinc.