pH of a Weak Acid Solution

Type of Acid

Select Acid:

OR

pK_a = K_a =
Molar mass = g/mol

Acid Conc. = g of acid / Liter of solution

OR

Molarity = M

pH at 25^oC =

[Acid] = [A^-] + [HA]
Weak acids have pK_a values in the range of −2 to 12.
In multiprotic weak acids, such as Citric acid, the contibution of secondary and further dissociations to the total [H⁺] is very small and, therefore, does not affect the pH of solution significantly. In this calculation, these secondary and tertiary dissocaitions are not considered.