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Tardigrade
Question
Chemistry
20 mL of 0.2 M sodium hydroxide solution is added to 40 mL of 0.2 M acetic acid solution. What is the pH of the solution? ( p Ka. of .CH 3 COOH =4.8)
Q.
20
m
L
of
0.2
M
sodium hydroxide solution is added to
40
m
L
of
0.2
M
acetic acid solution. What is the
p
H
of the solution?
(
p
K
a
of
C
H
3
COO
H
=
4.8
)
1468
202
AP EAMCET
AP EAMCET 2019
Report Error
A
9.2
B
4.8
C
8.4
D
2.9
Solution:
Given,
p
K
a
of
C
H
3
COO
H
=
4.8
Number of millimoles of
N
a
O
H
in
20
m
L
of
0.2
M
solution
=
20
×
0.2
=
4
mmol
Number of millimoles of
C
H
3
COO
H
in
40
m
L
of
0.2
M
solution
=
40
×
0.2
=
8
mmol
20
mmol of
0.2
M
,
N
a
O
H
will neutralise
20
mmol
of
0.2
M
acetic acid and produce
4
mmol of sodium acetate as follows:
C
H
3
COO
H
+
N
a
O
H
⟶
C
H
3
COON
a
+
H
2
O
That is equivalent to
4
mmol of sodium acetate.
Now,
p
H
=
p
K
a
+
lo
g
[
A
c
i
d
S
a
lt
]
p
H
=
p
K
a
+
lo
g
[
C
H
3
COO
H
[
C
H
3
COON
a
]
]
p
H
=
4.8
+
lo
g
[
4
]
[
4
]
p
H
=
4.8