A solution of glycerol `(C_(3)H_(8)O_(3))` in water was prepared by dissolving some glycerol in `500g` of water. This solution has a
boiling point of `100.42^(@)C` while pure water boils at `100^(@)C`. What mass of glycerol was dissolved to make the solution ?
(`K_(b)` for water `= 0.512 K kg mol^(-1)`)

Explanation

Elevation in boiling point .
`T_(b) = (k_(b) xx 1000 xx w_(B))/(w_(A) xx M_(B))`
` Delta T_(b) = 100.42 - 100= 0.42^(@) , w_(A) = 500g,w_(B) = ? , K_(b) = 0.512 K kg mol^(-1)`
`M_(B) = 3 xx 12+8 xx 1+ 3 xx 16 = 92`
` = 0.42 = (0.512 xx 1000 xx w_(B))/(500 xx 92)`
or `" " w_(B) = (0.42 xx 500 xx 92)/(0.512 xx 1000)`
` = 37.73 g`
Mass of glycerol to be added ` = 37.73 g`