Question

Which one of the following is true for any diprotic acid, $H _{2} X$ ?

• A. $Ka _{2}= Ka _{1}$
• B. $Ka _{2}> Ka _{1}$
• C. $Ka _{1}> Ka _{2}$
• D. $Ka _{2}=1 / Ka _{1}$

Answer 1

Answer: (C)

$H _{2} X \rightleftharpoons H ^{+}+ HX ^{-}\left( Ka _{1}\right) $
$HX ^{-} \rightleftharpoons H ^{+}+ X ^{2-}\left( Ka _{2}\right)$
So $Ka _{1}> Ka _{2}$