Vapour pressure of pure water at `27^@C` is 3000k Pa. By dissolving 5 g of a non volatile molecular solid in 100 g of water the vapour pressure is decreased to 2985 k Pa. What si the molecular weight of solute?

Explanation

According to Raoult.s law ,
`(p^@-p)/p^@=(wM)/(Wm) , (3000-2985)/3000=(5xx18)/(100xxm)`
Molecular weight of solute , `m=(5xx18xx30)/(100xx15)`=180 g .