The freezing point of benzene decreases by 0.450C when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be : (Kf for benzene=5.12 K kg mol−1)
Option: 1 74.6%
Option: 2 94.6
Option: 3 64.6%
Option: 4 80.4%
In benzene ,
t = 0 1 -
t = t 1 -
Given:
w = 0.2g W = 20 g T = 0.45 K
As we know ,
, observed M = 113.78 (acetic acid)
Molecular weight of acetic acid = 60
% degree of association = 94.5 %
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