Equilibrium Question 896

Question: If acetic acid is 1.0% ionised in its decinormal solution, then pH of its seminormal solution will be

Options:

A) 3.4

B) 4.8

C) 1.6

D) 2.6

Show Answer

Answer:

Correct Answer: D

Solution:

CH3COOH,CH3COO+,H+

Initial,conce.,11000After,t,time110110×1.0100110×1.0100110×1.0100,=0.1,=0.001=0.001

K=0.001×0.0010.1

=1×105 …(i) In case of seminormal solution CH3COOH,CH3COO,+H+

Initial,conc.1200After,t,time1212×x100,12×x100,12×x100

=0.5 [let solution is x ionised] K=(12×x100)20.5

=x220000 …(ii) From Eqs (i) and (ii) x220000=1×105

x=0.447

[H+]=12×x100

=12×0.447100=0.00224

pH=log,[H+]

=log,[0.00224]=2.65



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