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The vapour pressure of pure benzene at a certain tempreature is 0.850 bar. A non-volatile. non-electrolyte solid weighing 0.5g, when added to 39.0g of benzene (molar mass of benzene 78g mol^-1) vapour pressure of the solution then is 0.845 bar. What is the molar mass of the solid substance? |
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Answer» Solution :`"Given "P_(1)^(@)="0.850 bar,"w_(2)=0.5,""w_(1)=39.0,""m_(1)=78,""P_(1)="0.845 bar"` `(p_(1)^(@)-p_(1))/(p_(1)^(@))=(w_(2))/(m_(2))xx(m_(1))/(w_(1))` `=(0.850-0.845)/(0.850)=(0.5xx78)/(m_(2)xx39)` `THEREFORE M_(2)^(r)="170 g MOL"^(-1)` |
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