completely ionizes in water. However, the amount of a weak acid that has dissociated in water is not immediately obvious. In order to calculate the concentration of the weak acid at equilibrium, the fact that a decrease in the concentration of the acid corresponds to an increase both in the concentration of the hydronium ions and of the conjugate base must be used.
Example:
A 1M aqueous solution of nitrous acid is created and allowed to reach equilibrium. What is the pH of the final solution?
Nitrous acid ( ) is a weak acid (the strength of the acid can be determined from the implies that the acid is weak). In order to find the pH of the solution, the concentration of the hydronium ions must be found.
