The pH of a solution is related to the concentration of H+ ions in the solution by the following equation:
pH = -log[H+]
where [H+] is the concentration of H+ ions in moles per liter (M).
For the acid H2SO4, the dissociation can be written as follows:
H2SO4 ⇌ H+ + HSO4-
The acid dissociation constant, Ka, is defined as:
Ka = [H+][HSO4-]/[H2SO4]
Rearranging this equation gives:
[H+][HSO4-] = Ka[H2SO4]
Since the solution contains HSO4- ions, we can assume that all of the H2SO4 has dissociated, and therefore [H2SO4] = 0.15 M. We can also calculate the concentration of H+ ions using the pH:
pH = -log[H+]
10^(-pH) = [H+]
10^(-1.43) = [H+]
[H+] = 3.56 × 10^(-2) M
Substituting these values into the equation for Ka gives:
(3.56 × 10^(-2))(x) = Ka(0.15)
where x is the concentration of HSO4- ions. Solving for Ka:
Ka = (3.56 × 10^(-2))(0.15)/x
Ka = 5.34 × 10^(-3)/x
Therefore, the value of Ka depends on the concentration of HSO4- ions, which was not given in the problem. Without additional information, we cannot calculate the value of Ka.