Question

Calculate the amount of ice that will separate out on cooling a solution containing 50g of ethylene glycol in 200g water to `-9.3^(@)C` (`K_(f)` for water `= 1.86 "K kg mol"^(-1)`)

Answer 1

`DeltaT=K_(f)xxm`
`9.3=1.86xxm`
or`m=5`
Thus, solution of 5.0 molality will have freezing point of `-9.3^(@)C`. Let W g water be needed to prepare 5.0 molal solution containing `(50)/(62)` mole of ethylene glycol
SO, `(50xx1000)/(62xxW)=5.0`
or `W=(50xx1000)/(62xx5)=161.3g`
Hence, ice separating out `= (200 - 161.3) = 38.7g`]