Question

When 0.2M acetic acid is neutralised with 0.1M NaOH in 0.5 litre of water the resulting solution is slightly alkaline. Calculate the pH of the resulting solution. K a ​ for CH 3 ​ COOH=1.8×10 −5 .

Answer 1

Answer:

CHEMISTRY

When 0.2M acetic acid is neutralised with 0.1M NaOH in 0.5 litre of water the resulting solution is slightly alkaline. Calculate the pH of the resulting solution. K

a

for CH

3

COOH=1.8×10

−5

.

November 22, 2019avatar

Bellatrix Sree

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ANSWER

0.2M acetic acid will form 0.2M CH

3

COONa and 0.5 litre of water. Hence, concentration of sodium acetate [CH

3

COONa]=0.1molL

−1

CH

3

COO

−

+H

2

O⇌CH

3

COOH+OH

−

C(1−x) CxCx

K

h

=

(1−x)

Cx

2

=Cx

2

(1−x)→1

K

h

=

K

a

K

w

=

1.8×10

−5

1×10

−14

=5.5×10

−10

So, K

h

=Cx

2

=5.5×10

−10

or x

2

=55×10

−10

or x=7.42×10

−5

[OH

−

]=Cx=7.42×10

−5

×0.1=7.42×10

−6

M

[H

+

]=

[OH

−

]

K

w

=1.3477×10

−9

M

pH=−log[H

+

]=8.87