Formula pentru masa molara a amestecului este:
M=m/v, unde m-masa totala, iar v-cantitatea se substanta totala.
m=mCS2+mC3H8
mCS2/mC3H8=1/10=>mC3H8=10*mCS2, at
m=11*mCS2
v=vCS2+vC3H8
v=mCS2/M(CS2)+mC3H8/M(C3H8)
v=mCS2/M(CS2)+10*mCS2/M(C3H8)
v=mCS2*(1/M(CS2)+10/M(C3H8)), deci
M=11*mCS2/mCS2*(1/M(CS2)+10/M(C3H8))
M=11/(1/M(CS2)+10/M(C3H8))
Luand ca Ar(C)=12, Ar(S)=32, iar Ar(H)=1, obtinem M(CS2)=76g/mol, iar M(C3H8)=44g/mol, deci:
M=45,75g/mol
