How does size of molecule affect diffusion?

1 Answer
Dec 1, 2015

Answer:

#U_(rms)=sqrt((3RT)/(MM))#

Explanation:

The root mean square velocity (#U_(rms)#) of gas particles is given by the following expression:

#U_(rms)=sqrt((3RT)/(MM))#

where,
#U_(rms)# is the rate of diffusion
#R# is the universal gas constant
#T# is the temperature in kelvin
#MM# is the molar mass of the gas

To related this expression to the size of gas particles we can say that bigger size particles will possess high molar mass.

Since, #MM# is inversely proportional to the #U_(rms)#, thus when #MM# increases, the #U_(rms)# will decrease.

Therefore, we can conclude that bigger sized particles (heavy particles) will diffuse slower than lighter particles.