1.

A solution of sucross (molar mass = 342 g "mol"^(-1)) has been prepared by dissolving 68.4 g of sucrose in one kg of water. K_(f) for water is "1.86 K kg mol"^(-1) and vapour pressure of water at 298 K is 0.024 atm. The mass of sodium chloride that should be dissolved in the same amount of water to get the same freezing point will be

Answer»

136.8 g
32.2 g
5.85 g
11.60 g

Solution :`DeltaT_(f)=iK_(f)m therefore0.372=2xx1.86xxm or m =0.1`
THUS, 0.1 mole, i.e., 5.85 g of NACL should be dissolved in 1 KG of water.


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