The vapour pressure of pure bronze at a certain temparature is 262atm. At the same temparature the V.P. of a solution containing 2.0g of non-volatile solid in 100g bronze is 256atm . What is the molecular mass of the solid?

Explanation

We are given that
`p^(@)=262"atm",p_(s)=256"atm"`
`M_(1)=78"g/mol"` (Molar mass of benzene)
`W_(2)=2.0g,W_(1)=100g`
We are to calculate the molecular mass of the solute.
We know that
`(p^(@)-p_(s))/(p_(s))=(W_(2)M_(1))/(W_(1)M_(2)),(262-256)/(256)=(2.0gxx78"g/mol")/(100xxM_(2)),6/(256)=156/(100xxM_(2)),M_(2)=(156xx256)/(100xx6),M_(2)=66.5"g/mol"`