Question

If freezing point of water is depressed by
0.37°C in a 0.01 molal NaCl solution then freezing
point of 0.02 molal solution of urea is depressed by
0.37°C
O 0.74°C
O 0.185°C
O 0.57°C​

Answer 1

Answer:

As we know that,

Δtf=ikfm

where, Δtf = depression in freezing point

i=van't - Hoff factor

m=molarity

and kf=freezing point depression constant.

For 0.01 molal NaCl solution

0.37=2×kf×0.01

∴kf=2×0.010.37....(i)

For 0.02 molal urea solution

Δtf=1×kf×0.02

∴kf=0.02Δtf...(ii)

From Eqs (i) and (ii)

2×0.010.37=0.02Δtf

Δtf=2×0.010.37×0.02

∴tf=0.37

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