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12/10/2021 11:25 am
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The first and second dissociation constants of an acid H2A are 1.0 × 10–5 and 5.0 × 10-10 respectively. The overall dissociation constant of the acid will be
(a) 0.2 × 105
(b) 5.0 × 10-5
(c) 5.0 × 1015
(d) 5.0 × 10-15
1 Answer
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12/10/2021 11:34 am
Correct answer: (d) 5.0 × 10-15
Explanation:
H2A ⇌ H+ + HA-
∴ K1 = 1.0 x 10-5 = \(\frac{[H^+][HA^-]}{[H_2A]}\)
HA- → H+ + A2-
∴ K2 = 5.0 x 10-10 = \(\frac{[H^+][A^{2-}]}{[HA^-]}\) (Given)
K = \(\frac{[H^+][A^{2-}]}{[H_2A]}\)
= K1 x K2
= (1.0 x 10-5) x (5.0 × 10-10) = 5.0 × 10-15
This post was modified 3 years ago by Mayank1444