Evaporation, Vapour pressure and Boiling Kya Hai?
Evaporation Kya Hai?
Evaporation is the “spontaneous escape of molecules from a liquid surface at any temperature.”
It occurs at all temperatures and is a surface phenomenon.
At any temperature, the energy of the molecules in a liquid is not equal, and this causes them to flow at various speeds. High-energy molecules that collide with molecules on a liquid’s surface release some of their energy, enabling the surface molecules to overcome the forces of attraction and move away from the liquid’s surface. Evaporation occurs in this way. Average kinetic energy increases as high-energy molecules depart from the liquid surface. The remaining molecules’ energy declines, causing the temperature to drop. Evaporation results in cooling because of this.
Vapour Pressure Kya Hai?
Vapour pressure is defined as the force applied by a liquid’s vapours at a specific temperature when the equilibrium between evaporation and condensation has been reached.
Think about a liquid contained in a small space. The pace of evaporation will start off quickly and there won’t be any condensation. However, as time goes on, the rate of evaporation slows down while the rate of condensation picks up speed. Eventually, the two rates balance out, equilibrium is reached, and the amount of vapours remains constant. Vapour pressure is the force that vapours produce when they are in equilibrium.
Boiling Point Kya Hai?
Some liquids have boiling points, which are defined as “the temperature at which the vapour pressure of a liquid equals the atmospheric or external pressure.” The phenomenon of conversion of liquid at its boiling point is called boiling.
Boiling begins at this point as the vapour pressure reaches air pressure or external pressure as a result of rising temperature. Despite continual heat supply, the temperature remains constant at boiling. When heat is present before boiling point, it is used to enhance P.E. and K.E., respectively. The temperature rises as K.E grows. However, at boiling point, all of the heat energy supplied is used to increase P.E. and K.E. remains constant, maintaining a constant temperature.