The first and second dissociation constants of an acid H_2A are 1.0 × 10^-5 and 5.0 × 10^-10 respectively. The overall dissociation constant of the ac - Chemistry MCQ AIEEE 2007 2026 | ExamTest.live

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The first and second dissociation constants of an acid H_{2} A are 1.0 \times 1 0^{- 5} and 5.0 \times 1 0^{- 10} respectively. The overall dissociation constant of the acid will be:

Solution & Step-by-step Explanation

The stepwise dissociation of H_{2} A is: H_{2} A ⇌ H^{+} + HA^{-} K_{1} = \frac{[ H ^{+} ] [ HA ^{-} ]}{[ H _{2} A ]} HA^{-} ⇌ H^{+} + A^{2 -} K_{2} = \frac{[ H ^{+} ] [ A ^{2 -} ]}{[ HA ^{-} ]} The overall dissociation reaction is: H_{2} A ⇌ 2 H^{+} + A^{2 -} K = \frac{[ H ^{+} ] ^{2} [ A ^{2 -} ]}{[ H _{2} A ]} Multiplying K_{1} and K_{2} : K_{1} \times K_{2} = \frac{[ H ^{+} ] [ HA ^{-} ]}{[ H _{2} A ]} \times \frac{[ H ^{+} ] [ A ^{2 -} ]}{[ HA ^{-} ]} = \frac{[ H ^{+} ] ^{2} [ A ^{2 -} ]}{[ H _{2} A ]} = K K = (1.0 \times 1 0^{- 5}) \times (5.0 \times 1 0^{- 10}) = 5.0 \times 1 0^{- 15}

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The first and second dissociation constants of an acid H_{2} A are 1.0 \times 1 0^{- 5} and 5.0 \times 1 0^{- 10} respectively. The overall dissociation constant of the acid will be:

5.0 \times 1 0^{- 5}

5.0 \times 1 0^{15}

5.0 \times 1 0^{- 15}

5.0 \times 1 0^{5}

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