When 9 . 45   g of ClCH 2 COOH is added to 500   mL of water, its freezing point drops by 0 . 5…

When 9.45 g of ClCH2COOH is added to 500 mL of water, its freezing point drops by 0.5°C. The dissociation constant of ClCH2COOH is x×10-3. The value of x is off to the nearest integer)

KfH2O=1.86 K kg mol-1

Solution

ClCH2COOH⇌ClCH2COO⊖+H+

i=1+(2-1)α

i=1+α

ΔTf=i.Kf.m

0.5=(1+α)(1.86)9.4594.55001000

53.72=1+α⇒α=1.283.72

α=3293

Ka=Cα2C−Cα=Cα21−αC=0.1500/1000=0.2

Ka=0.232/9321−32/93=0.2×32293×61

=0.036

Ka=36×10−3

Asked in: JEE Main 2021 (24 Feb Shift 1)

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