A solution of `0.643 g` of an organic compound in `50 mL` of benzene (density `0.879 g//mL`) lowered its freezing point from `5.51^(@)C` to `5.03^(@)C`. Calculate the molecular weight of solid. `(K_(f)` for benzene is `5.12 K mol^(-1) kg`)

Answer

156.06

Explanation

Organic compound-B ,Water-A
`"W"_("A")="P"_("A")xx"V"_("A")`
`=0.879xx50`
`=44"gm (App)"`
`"m"_("B")=(1000"K"_("f")"w"_("B"))/("w"_("A")xxDelta"T"_("f"))`
`=(1000xx5.12xx0.643)/(44xx0.48)`
`=156.06"gm mol"^(-1)`