Define latent heat of vaporization.
Difficulty: Easy
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 $H_{v}$.
$H_{v} = \frac{ (\triangle Q_{v})}{m}$
Or $\triangle Q_{v} = m H_{v}$ ………… (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 $2.26 \times 10^{6}$ $Jkg^{-1}$ . That is; one kilogram of water requires $2.26 \times10^{6}$ joule heat to change it completely into a gas (steam) at its boiling point.
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