Acetic acid, HC2H3O2 is monoprotic. A 0.010M solution of lactic acid has a pH 2.44. calculate the ionization constant, Ka, for this acid
To calculate the ionization constant (Ka) for lactic acid, we will use the equation for Ka:
Ka = [H+][C2H3O2-] / [HC2H3O2]
First, we need to determine the concentrations of the species involved. In this case, we know the pH of the solution, which is 2.44. The pH is related to the concentration of H+ ions by the equation:
pH = -log[H+]
Therefore, we can calculate the concentration of H+ ions using the pH:
[H+] = 10^(-pH)
[H+] = 10^(-2.44)
Next, we need to find the concentration of HC2H3O2. In this case, we know that it is a 0.010 M solution of lactic acid. Therefore, the concentration of HC2H3O2 is 0.010 M.
Finally, we need to find the concentration of the C2H3O2- ions. Since lactic acid is monoprotic, all of the HC2H3O2 will ionize to form C2H3O2- ions:
[C2H3O2-] = [HC2H3O2] = 0.010 M
Now that we have all the concentrations, we can substitute them into the equation for Ka:
Ka = ([H+][C2H3O2-]) / [HC2H3O2]
Ka = (10^(-2.44) * 0.010) / 0.010
Simplifying:
Ka = 10^(-2.44)
Using a calculator, we find:
Ka ≈ 4.12 x 10^(-3)
So, the ionization constant (Ka) for lactic acid in this 0.010 M solution is approximately 4.12 x 10^(-3).