19. The K, value for HCN is 10power 9. What is the pH of 0.4 m HCN solution?
Answers
Answered by
0
Answer:
HCN⇌H
+
+CN
−
0.1
0.1(1−α) 0.1α 0.1α
K
a
=
0.1(1−α)
(0.1α)(0.1α)
It is given that pH=10.5 so −log([H
+
])=5.2
[H
+
]=6.3×10
−6
=0.1α
α=6.3×10
−5
K
a
=
0.1(1−α)
(0.1α)(0.1α)
As α<<1 so 1−α=1
K
a
=0.1α
2
=3.97×10
−10
Answered by
0
Answer:
Ka =10-9
c = O.4M
pH = – log [H+]
∴ pH = – log(2 x 10-5)
= – log 2 – log (10-5)
= – 0.3010 + 5
pH = 4.699
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