Question

What is a vapour pressure of liquid?
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Answer 1

Answer:

(1) fa volatile liquid is placed in an open vessel, the liquid molecules have a tendency to escape in a gaseous state forming vapour and difuse into surroundings. lence evaporation takes place continuously, and no equilibrium is atained.

(2) If a liquid is placed in a closed vessel, the vapour molecules get accumulated on ts Surface. Thesc vapour molecules are n continuous random motion. They collide with each other, with walls of a

container and surface of the liquid, and return to the liquid state. This reverse phenomenon is called condensation.

3) ATter some time, rates of evaporation and condensation become equal and an equilibrium is established between liquid and vapour phases. At this stage the vapour exerts a constant pressure called vapour pressure on iquid surface at constant temperature.

4) Vapour pressure: The pressure exerted by the vapour of a liquid (or solid) when it is in equilibrium with the liquid (or solid) phase at a constant temperature is called the vapour pressure of the liquid (or solid).

(5) The vapour pressure of a hquid increases with the increase in temperature.

Answer 2

define vapour pressure of a liquid:

when a liquid in a closed container is in equilibriumwith its vapours, the pressure exerted by the vapour on the liquid is its vapour pressure.