Question

Which produces more burn, steam or boiling water?
A.Steam
B.Boiling water
C.Both produce same burn
D.Data insufficient

Answer 1

Hint: The latent heat of vaporization is responsible for the steam possessing more thermal energy than boiling water, at the same temperature. It is the amount of heat required to raise the temperature of \[1{\text{ Kg}}\] of water in the liquid state by ${1^0}{\text{C}}$.

Complete step by step solution:
Steam possesses more heat than boiling water even though they are at the same temperature. This is due to the latent heat of vaporization of steam which can be defined as the amount of heat required to raise the temperature of \[1{\text{ Kg}}\] of water in the liquid state by ${1^0}{\text{C}}$.
The word latent heat actually means “hidden” and it is called so because this heat cannot be measured using any instrument. This heat is used to increase the internal energy of the water molecules so that their potential energy increases and the van der Waals force of attraction between the water molecules as well as the hydrogen bonding in them, which is the main reason behind the water molecules being liquid. Hence the steam at any point will possess more heat than boiling water.
So, steam should produce more burn than boiling water.

Hence, the correct option is option A.

Note:
A specific latent heat $\left( {\text{L}} \right)$ expresses the amount of heat $\left( {\text{Q}} \right)$ required to completely effect a phase change of a unit mass, $\left( {\text{m}} \right)$ usually \[1{\text{ Kg}}\] of a substance as an intensive property: $\left( {\text{L}} \right)$ = $\dfrac{{\text{Q}}}{{\text{m}}}$
Intensive properties are material characteristics and are not dependent on the size or the extent of the particles. The commonly used unit of specific heat is ${\text{KJ/Kg}}$.