Define latent heat of vaporization.

Question

Define latent heat of vaporization.

Accepted Answer

Latent heat of vaporization:

The quantity of heat that changes the unit mass of a liquid completely into as at its boiling point without any change in its temperature is called its latent heat of vaporization.

It is denoted by $H_{v}$.

$H_{v} = \frac{ ( riangle Q_{v})}{m}$

Or $ riangle Q_{v} = m H_{v}$ ………… (i)

When water is heated, it boils at 100°C under standard pressure. Its temperature remains 100°C until it is changed completely into steam. Its latent heat of vaporization is $2.26 imes 10^{6}$ $Jkg^{-1}$ . That is; one kilogram of water requires $2.26 imes10^{6}$ joule heat to change it completely into a gas (steam) at its boiling point.