Question

4 (1 Point) The hydrogen oxalate ion, HC,04 , is amphiprotic. The predominant reaction is.... A. HC204 + H20 <=> OH + H2C204 because K<Ky B. HC204+H,0 <=> H2O+ + C20 - because K, <Kb C. HC204 + H20 <=> OH- + H2C2O4 because K > D. HC,04 +1,0 <=> H2O+ + C2022-because K >K > Кь А B С

Answer 1

H2C204 is a diprotic acid. The First dissociation of H2C204 can be shown as below H2C204 (aq) HC204- (aq) + H+ (aq)

or

H2C2O4 (aq) + H2O (l) < ------ > HC2O4 - (aq) + H3O+ (aq)

for this reaction Ka1 = 5.4*10^-2

assume the reaverse reaction, HC2O4- (aq) + H2O (l) < ------ > H2C2O4 (aq) + OH- (aq)

for the above base dissociation reaction k b = kw / Ka1 = 10 ^-14 / 5.2 * 10 ^ -2 = 1.92 * 10^-13

The second dissociation of H2C204 can be shown as below HC204 - (aq) C204-2(aq) + H+ (aq)

HC2O4 - (aq) + H2O (l) < ------ > C2O4 2- (aq) + H3O+ (aq)

for this reaction Ka2 = 6.4 *106-5

so the acid dissocition constant for HC2O4 > base dissociation constant

i.e Ka > Kb

so answer is D