Question

In a 0.01 M solution of 1,4-butanedicarboxylic acid, HOOCCH2CH2COOH (Ka1 = 2.9 x 10-5,

Ka2 = 5.3 x 10-6), which species is present in the highest concentration?
A) HOOCCH2CH2COO-(aq)
B) HOOCCH2CH2COOH(aq)
C) H3O+(aq)
D) -OOCCH2CH2COO-(aq)
E) OH-(aq)

Answer 1

The correct answer is B) HOOCCH2CH2COOH(aq)

Step-by-step explanation:

Both Ka1 and Ka2 are low, so the acid will dissociate only slightly into HOOCCH2CH2COO- ions and even more slightly into -OOCCH2CH2COO- ions. The concentration of hydronium ions (H₃O⁺) will be consequently low. The species that will be in the highest concentration will be HOOCCH2CH2COOH (the weak acid not dissociated).