Choose the correct statement with respect to the vapour pressure of a liquid among the following :
- Increases non-linearly with increasing temperature
- Decreases non-linearly with increasing temperature
- Decreases linearly with increasing temperature
- Increases linearly with increasing temperature
Solution
The pressure exerted by the vapors over the liquid surface when liquid and vapour are in equilibrium is called vapour pressure. Vapour pressure increases with an increase with temperature.
Average kinetic energy of the gas molecules is directly proportional to the absolute temperature. At higher temperatures, more molecules from the liquid have enough KE to escape from the surface of the liquid. Which will increase vapor pressure.
For phase equilibrium for liquid & vapour phases
The relation between temperature and vapor pressure is given by the Clausius-Clapeyron equation.
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ie. vapour increases exponentially with rise in temp ie.
Non linear increase.
Asked in: JEE Main 2014 (19 Apr Online)