pKa(H2CO3) = 6.33
Consider 0.040 H2CO3.
| Ka = | [HCO3–][H3O+] |
| [H2CO3] |
HCO3– + H3O+Calculating the pH:
pKa and pH are related through the Ka expression
pKa and pH are related through the Ka expression
and
the reaction occurring to reach equililbrium.Enter formulae in these three spaces.
| 4.68 × 10–7 = | [H3O+] [H3O+] |
| 0.04 |
[H3O+] = 1.37 × 10–4
pH = 3.86
Substituting from above into Ka expression:
Enter numbers at the left of the = (2 dp).
Enter an ion formula in the numerator.
Enter a number in the denominator.
Enter an ion formula in the numerator.
Enter a number in the denominator.
Note that for a solution in which the concentration of the acid of the pair is much higher than the base of the pair the pH is not only lower than 7 but also lower than pKa for the conjugate pair.