Question

The latent heat of vaporization of water is:
A. \[2.25 \times {10^6}J/kg\]
B. \[2.25 \times {10^8}J/kg\]
C. \[2.25 \times {10^4}J/kg\]
D. \[2.25 \times {10^{ - 6}}J/kg\]

Answer 1

Hint: Latent heat of vaporization is defined as the heat required to change 1 mole of liquid substance into gaseous form under standard atmospheric pressure. The value of heat of vaporization of water is equal to 40.8KJ/mol.

Complete step by step answer:
-There are three states of matter: Solid, liquid and gases. When a substance changes from one phase to another phase, the transition is known as phase change or phase transition. Examples: Changes from solid to liquid, liquid to gas, gas to liquid, solid to gas are known as phase change. During the phase change, it involves the transfer of heat.
-This transfer of heat is known as latent heat. The latent heat is defined as the energy released or absorbed by a system at a constant temperature.
-The example of latent heat is heat of freezing and heat of vaporization.
-The heat of freezing is defined as the amount of thermal energy released as liquid freezes and heat of vaporization is defined as the amount of thermal energy added when liquid changes to gas.
-Latent heat of vaporization is a physical property which is defined as the heat required to change 1 mole of liquid substance into gaseous form.
-The heat of vapourization at \[100^\circ C\] is 2,250 joules per gram or \[2.25 \times {10^6}J/kg\].
Therefore, the correct option is A.

Note:
The transfer of heat during the phase change takes place even when the temperature of the substance which undergoes the phase change remains constant. The latent heat is first order phase transition.