دیا
3 The dissociation Constant of bezoic acid
(Colo CooH) is 6.6 x los calculate than
hydrogen ion concentration of a Solution
Containing 1.22 gm of benzoic acid in 2000ml
of coater
Answers
Explanation:
Since pH=3.19
[H
3
O
+
]=6.46×10
−4
M
C
6
H
5
COOH+H
2
O⇋C
6
H
5
COO
−
+H
3
O
K
a
=
[C
6
H
5
COOH]
[C
6
H
5
COO
−
][H
3
O
+
]
[C
6
H
5
COO
−
]
[C
6
H
5
COOH]
=
K
a
[H
3
O
+
]
=
6.46×10
−5
6.46×10
−4
=10
Let the solubility of C
6
H
5
COOAg be x mol/L
Then,
[Ag
+
]=x
[C
6
H
5
COOH]+[C
6
H
5
COO
−
]=x
10[C
6
H
5
COO
−
]+[C
6
H
5
COO
−
]=x
[C
6
H
5
COO
−
]=
11
x
K
sp
[AG
+
][C
6
H
5
COO
−
]
2.5×10
−13
=x(
11
x
)
x=1.66×10
−6
mol/L
Thus, the solubility of silver benzoate in a pH 3.19 solution is 1.66×10
−6
mol/L
Now, let the solubility of C
6
H
5
COOAg be x
′
M
Then, [Ag
+
]=x
′
M and [C
6
H
5
COO
−
]=x
′
M
K
sp
=[Ag
+
][C
6
H
5
COO
−
]
K
sp
=(x
′
)
2
x
′
=
K
sp
=
2.5×10
−13
=5×10
−7
mol/L
∴
x
′
x
=
5×10
−7
1.66×10
−6
=3.32
Hence, C
6
H
5
COOAg is approximately 3.32 times more soluble in low pH solution.