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The average molar mass of a mixture of methane (CH_(4)) and ethene (C_(2)H_(4)) present in the ratio of a:b is found to be 20.0g mol^(-1). If the ratio were reversed, what would be the molar mass of the mixture ? |
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Answer» Solution :Molar MASS of `CH_(4)="16 g mol"^(-1)` `"Molar mass of "C_(2)H_(4)="28 g mol"^(-1)` When they are PRESENT in the raio `a : b`, their AVERAGE molar mass`=(axx16+bxx28)/(a+b)="20 g mol"^(-1)` (Given) i.e., `16a+28b=20(a+b) or 4a+7b=5(a+b) or a=2b or (a)/(b)=(2)/(1)=2:1` If the ratio is REVERSED, now the ratio `a:b=1:2` `therefore"Average molar mass"=(1xx16+2xx28)/(1+2)=(16+56)/(3)=(72)/(3)="24 g mol"^(-1)` |
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