Ethylene glycol (C_(2) H_(6) O _(2)) can be used as an antifreeze in the radiator of a car. Calculate the temperature when ice will begin to separate from a mixture with 20 mass percent of glycol in water used in the car radiator. K_(f) for water = 1.86 K kg mol^(-1) and molar mass of ethylene glycol is 62 g mol ^(-1).

Ethylene glycol (C_(2) H_(6) O _(2)) can be used as an antifreeze in t

1.	Ethylene glycol (C_(2) H_(6) O _(2)) can be used as an antifreeze in the radiator of a car. Calculate the temperature when ice will begin to separate from a mixture with 20 mass percent of glycol in water used in the car radiator. K_(f) for water = 1.86 K kg mol^(-1) and molar mass of ethylene glycol is 62 g mol ^(-1).
Answer» Solution :Weight of solute `(W_(2))=20` mass PERCENT of solution means 20g of ethylene glycol Weight of SOLVENT (water) `W_(1) = 100 -20=80g` `Delta T_(f) = K _(f) m = (K _(f) xx W_(2) xx 1000)/( M _(2) xx W _(1)) = (1. 86 xx 20 xx 1000)/(62 xx 80) = 7.5 K` The temperature at which the ICE will begin to separate is the freezing of water after the addition of solute i.e. `7.5K` lower than the normal freezing point of water `(273 - 7.5) K = 265.5K`