Question

Dissociation of an aqueous acid (HA) gives HA + H2O H3O + + A- , then pKa is

Answer 1

---------Acids and Bases

Acidity Constant (Ka)

¾ Acids differ in their H+ donating ability

¾ Measured based on their ability to

donate H+ to water

H-A + H2O A- + H3O+

¾Position of the eq. relates to acid strength

•equilibrium favors the rhs ⇒ strong acid

•equilibrium favors the lhs ⇒ weak acid

-----------Acids and Bases

¾ quantified by measuring the eq. constant

¾ often expressed as pKa (= -log Ka)

H-A + H2O A- + H3O+

Keq = [H3O+] [A-] [HA] [H2O] Ka = [H3O+ ] [A- ]