Correct Option
The correct option isSteam at 100°C
Explanation
The severity of a burn depends on the amount of heat energy transferred to the skin. This phenomenon is governed by the concept of Latent Heat of Vaporization, which represents the energy absorbed or released during a phase change between liquid and gas at a constant temperature.
Detailed Analysis
- Energy Content: Both boiling water and steam exist at 100°C. However, steam possesses significantly higher internal energy than boiling water at the same temperature.
- Latent Heat: To convert water at 100°C into steam at 100°C, heat energy (approximately 540 cal/g or 2260 J/g) is supplied. This energy is stored in the steam as Latent Heat of Vaporization.
- Mechanism of Burn: When steam comes into contact with the skin, it condenses back into water at 100°C. During this phase change, it releases the large amount of latent heat it had absorbed. Following condensation, the hot water continues to release heat as it cools down to skin temperature.
- Comparison: Boiling water at 100°C does not undergo this phase change (condensation) upon contact; it only releases heat as it cools down. Therefore, the total heat energy transferred by steam is the sum of the latent heat and the heat released during cooling, whereas boiling water only transfers the latter.
Key Takeaway: Steam causes more severe burns than boiling water at the same temperature because steam contains additional heat energy in the form of Latent Heat of Vaporization.