Question

Kinetic theory of gases proves
(a) only Boyle's law
(b) only Charles' law
(c) only Avogadro's law
(d) all of these.

Answer 1

(d) : Explanation of the Gas Laws on the basis of Kinetic Molecular Model One of the postulates of kinetic theory of gases is

(i) Boyle’s Law :

•  Constant temperature means that the average kinetic  energy of the gas molecules remains constant.
• This means that the rms velocity of the molecules, C_rms remains unchanged.
• If the rms velocity remains unchanged, but the volume increases, this means that there will be fewer collisions with the container walls over a given time.
• Therefore, the pressure will decrease

(ii) Charles’ Law : 

•  An increase in temperature means an increase in the average kinetic energy of the gas molecules, thus an increase in c_rms. 
• There will be more collisions per unit time, furthermore, the momentum of each collision increases (molecules strike the wallharder). 
• Therefore, there will be an increase in pressure. 
• If we allow the volume to change to maintain constant pressure, the volume will increase with increasing temperature (Charles law). 

(iii) Avogadro’s Law 

It states that under similar conditions of pressure and temperature, equal volume of all gases contain equal number of molecules. Considering