d formula 2 b used is

(C1n1+C2n2)/n1+n2

 

n=moles

C=Cv orCp

 

actually realisingand finding straight away formulas using gamma and C is difficult... and may lead to confusion

so better way is to do with degree of freedom..

 

degree of freedom is origin of all and is difined per molecule .... so is the basic thng and can be used in max. cases...

 

so net degree of freedom f ' =   N1 (f1) + N2 (f2)+......

 

here f1 and f2..... all are degrees of freedom per molecule of diff gases....

moles can definitely be expressed as molefraction also

lik       f ' = X1 f1  +   X2 f2............

 

whre X1 X2 are mole fractions...

thn Cv =  f'/2

use Cv to find gamma

 

 deg of freedom per molecule and hence here can be used per mole bcos everytime an avagadro no. ud appear in numerator and dinominator which gets cancelled

 

 

Cheers!!!!!!