Asolution is prepared by dissolving 215 grams of methanol, ch3oh, in 1000. grams of water. what is the freezing point of this solution? [the freezing point depression constant for water is 1.86°c/mole solute in 1000g of water]

Answer : The freezing point of the solution is, 260.503 K

Solution : Given,

Mass of methanol (solute) = 215 g

Mass of water (solvent) = 1000 g = 1 kg       (1 kg = 1000 g)

Freezing depression constant =

Formula used :

where,

= freezing point of water =

= freezing point of solution

= freezing point constant

= mass of solute

= mass of solvent

= molar mass of solute

Now put all the given values in the above formula, we get

By rearranging the terms, we get the freezing point of solution.

Therefore, the freezing point of the solution is, 260.503 K

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"