Name: Concept of Viscosity
Uploaded: 2019-07-19
Duration: 4 min 40 s
Description: This video describes the chemistry behind viscosity and why it is different between various liquids. Let us learn this concept from this informative video.

Question

Define and explain the term vapour pressure.

Accepted Answer

When a liquid is placed in an open vessel exposed to the atmosphere, it gradually disappears. The change of a liquid into a gas is known as evaporation. At constant temperature, when the evaporation of a liquid takes place in a closed container, the molecule that escapes from the surface of the liquid are trapped in the container and occupy the space above the surface of the liquid. The molecules collide with each other and with the walls of the container. A few of them may also hit the surface of the liquid and return to it resulting in condensation. The rate of return of molecules in the vapour state is proportional to the concentration of molecules in the vapour state. Finally, a stage reaches when both rates are equal.

Vapour pressure of the liquid at any temperature is the pressure exerted by the vapour of the liquid when it is in equilibrium with the liquid. Vapour pressure increases with an increase in temperature.

Define and explain the term vapour pressure.

Important Questions on States of Matter : Liquid State

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