Question

$Ka _1, Ka _2$ and $Ka _3$ are the respective ionization constants for the following reactions (a), (b) and (c)
(a) $H _2 C _2 O _4 \rightleftharpoons H ^{+}+ HC _2 O _4^{-}$
(b) $HC _2 O _4^{-} \rightleftharpoons H ^{+}+ HC _2 O _4^{2-}$
(c) $H _2 C _2 O _4 \rightleftharpoons 2 H ^{+}+ C _2 O _4^{2-}$
The relationship between $K _{ a _1}, K _{ a _2}$ and $K _{ a _3}$ is given as

• A. $K _{ a _3}= K _{ a _1}+ K _{ a _2}$
• B. $K _{ a _3}= K _{ a _1}- K _{ a _2}$
• C. $K _{ a _3}= K _{ a _1} / K _{ a _2}$
• D. $K _{ a _3}= K _{ a _1} \times K _{ a _2}$

Answer 1

Answer: (D)

$K _{ a _3}= K _{ a _1} \times K _{ a _2}$

Answer 2

H2​C2​O4​⇌H++HC2​O4−​Ka1​​
H2​C2​O4−​⇌H++C2​O42−​Ka2​​
H2​C2​O4​⇌2H++C2​O42−​Ka3​​=Ka1​​×Ka2​​