Question:
Water as ice has a cooling effect whereas water as steam may cause severe burns. Explain these observations.
Solution:
Both ice and steam are the physical states of the same substance i.e. water. However, they differ in their nature. Ice on coming in contact with skin (at a higher temperature) absorbs energy as latent heat of fusion from the skin and melts. Since energy has been taken up from the body, a cooling sensation is experienced. But when steam comes in contact with the skin (lower temperature) it releases energy which causes severe burns on the skin.