Just about everyone at one time or another has been burned by hot water or steam.?
This problem compares the heat input to your skin from steam as opposed to hot water at the same temperature.
Assume that water and steam, initially at 100∘C, are cooled down to skin temperature, 34∘C, when they come in contact with your skin. Assume that the steam condenses extremely fast. We will further assume a constant specific heat capacity c=4190J/(kg⋅K) for both liquid water and steam.
How much heat H1 is transferred to the skin by 25.0 g of steam onto the skin? The latent heat of vaporization for steam is L=2.256×106J/kg
- 4 years ago
Note that the amount of energy absorbed by the skin due to steam is nearly 10 times the amount absorbed by water. This is the reason why steam burns are more painful as compared to burns by boiling water. Also note that the temperature of steam may be much more than that of water.Source(s): Mastering Physics
- 5 years ago
First steam turns to liquid water:
Heat (Ha) transferred to skin when 25.0 g of steam at 100°C is turned into water at 100°C
Ha = mass * L = (0.025 kg * 2.256×106J/kg) = 5.64 * 10^4 joules
Then water cools from 100°C to 34°C
Hb = mass * c * ΔT
Hb = 0.025 * 4190 * (100°C - 34°C) = 6913.5 joules
Total heat transferred = H1 = Ha + Hb ≈ 63314 J