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Tardigrade
Question
Chemistry
What is [ H +]in mol/L of a solution that is 0.20 M in CH 3 COONa and 0.10 M in CH 3 COOH ? (Ka text for CH 3 COOH =1.8 × 10-5)
Q. What is
[
H
+
]
in mol/L of a solution that is
0.20
M
in
C
H
3
​
COON
a
and
0.10
M
in
C
H
3
​
COO
H
?
(
K
a
​
 forÂ
C
H
3
​
COO
H
=
1.8
×
1
0
−
5
)
12585
219
AIPMT
AIPMT 2010
Equilibrium
Report Error
A
3.5
×
1
0
−
4
8%
B
1.1
×
1
0
−
5
10%
C
1.8
×
1
0
−
5
13%
D
9.0
×
1
0
−
6
69%
Solution:
C
H
3
​
COO
H
(weak acid) and
C
H
3
​
COON
a
(conjugated salt) form acidic buffer and for acidic buffer
p
H
=
p
K
a
​
+
lo
g
[
 acidÂ
]
[
 saltÂ
]
​
and
[
H
+
]
=
−
antilogÂ
p
H
p
H
=
−
lo
g
K
a
​
+
lo
g
[
 acidÂ
]
[
 saltÂ
]
​
[
∴
p
K
a
​
=
−
lo
g
K
a
​
]
=
−
lo
g
(
1.8
×
1
0
−
5
)
+
lo
g
0.10
0.20
​
=
4.74
+
lo
g
2
=
4.74
+
0.3010
=
5.041
Now,
[
H
+
]
=
antilog
(
−
5.045
)
=
9.0
×
1
0
−
6
 molÂ
/
L