Gas X has a mass of 28.02 amu and gas Y has a mass of 32 amu. Which gas will diffuse faster?

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Answer 1 · 2016-08-19T08:49:32

The two gases will almost diffuse at the same speed.

The root mean square velocity (#U_(rms)#) of a gas is found by:

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

where, #MM# is the molar mass of the gas.

If you have two gases, X and Y, the ratio between their #U_(rms)# can be determined by:

#(U_X)/(U_Y)=sqrt((MM_Y)/(MM_X))#

#=>(U_X)/(U_Y)=sqrt((32)/(28.02))=1.068~=1.1 ("2 significant figures")#

Therefore, the two gases will almost diffuse at the same speed.