Question

1. Net ionic equation before the equivalence point:

CO₃^2-(aq) + H⁺ (aq) <--> HCO₃^-(aq) K= 1.8 x 10¹⁰

What is the relationship between this reaction (above) and this reaction (below)?

HCO₃^-(aq) + H₂O(l) <--> H₃O⁺(aq) + CO₃^2-(aq) K= 5.6 x 10^-11

2. Net ionic equation after the equivalence point:

HCO₃^-(aq) + H⁺(aq) <--> H₂CO₃(aq) K= 2.3 x 10⁶

What is the relationship between this reaction (above) and this reaction (below)?

H₂CO₃(aq) + H₂O (l) <--> H₃O⁺(aq) + HCO₃^-(aq) K= 2.6 x 10^-4

Answer 1

1)

Net ionic equation before the equivalence point:

RXN1: CO₃^2-(aq) + H⁺ (aq) <--> HCO₃^-(aq)    say K1 = 1.8 x 10¹⁰

RXN2: HCO₃^-(aq) + H₂O(l) <--> H₃O⁺(aq) + CO₃^2-(aq)    say K2 = 5.6 x 10^-11

Let,s have,

K1 * K2 = (1.8 x 10¹⁰) * (5.6 x 10^-11)

K1 * K2 = 1    (apprx.)

K1 = 1 / K2

Hence we can say that RXN 2 is the reverse reaction of RXN2.

Or If, RXN 1 is forward reaction then RXN 2 is Reverse reaction.

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2. Let,

RXN1: HCO₃^-(aq) + H⁺(aq) <--> H₂CO₃(aq) say K1 = 2.3 x 10⁶

RXN2: H₂CO₃(aq) + H₂O (l) <--> H₃O⁺(aq) + HCO₃^-(aq) say, K2 = 2.6 x 10^-4

RXN 1 is forward reaction then RXN 2 is Reverse reaction.

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