Question

In a 0.010M solution of oxalic acid, $ {{H}_{2}}{{C}_{2}}{{O}_{4}}, $ $ {{K}_{1}}=5.9\times {{10}^{-2}}, $ $ {{K}_{{{a}_{2}}}}=6.4\times {{10}^{-5}}, $ the species present in the lowest concentration is

• A. $ {{H}_{2}}{{C}_{2}}{{O}_{4}} $
• B. $ {{H}_{3}}{{O}^{+}} $
• C. $ HC{{r}_{2}}O_{4}^{-} $
• D. $ CrO_{4}^{2-} $

Answer 1

Answer: (D)

Due to very small value of $ {{K}_{{{a}_{2}}}}, $ the second ionisation will be very less and in solution, oxalate ion $ {{(C{{r}_{2}}{{O}_{4}})}^{2-}} $ will be at lowest concentration.