`30mL` of `CH_(3)OH (d = 0.7980 g cm^(-3))` and `70 mL` of `H_(2)O (d = 0.9984 g cm^(-3))` are mixed at `25^(@)C` to form a solution of density `0.9575 g cm^(-3)`. Calculate the freezing point of the solution. `K_(f)(H_(2)O)` is `1.86 kg mol^(-1)K`. Also calculate its molarity.

Answer

`-19.91^(@)C, 7.63M`

Explanation

`CH_(3) OH rarr V_(1) = 30 mL, d_(1) = 0.798 g//mL`
`m_(1) = 23.94 g`
`H_(2)O rarr V_(2) = 70 mL, d_(2) = 0.9984 g//mL`
`m_(2) = 69.888g`
`m_(T) = 93.828g`
`d_("solution") = 0.9575 g//mL`
`V_("solution") = 98 mL`
`DeltaT_(f) = (1.86 xx 23.94 xx 1000)/(32xx 69.888) = 19.91`
`T_(f) =- 19.91^(@)C`
`M = (23.94)/(32 xx 0.98) = 7.63M`