How do you calculate percent dissociation?
Divide the mass of dissociated ions by the total mass of dissociated and undissociated species; then multiply by 100 percent.
You can do this by moles, too, if you use the proper coefficients from the balanced reaction.
Example: When 0.5 mol of acetic acid is dissolved in enough water to make 1 liter of solution, the measured pH is 2.5. What is the percent dissociation of the acid?
Concentration of ionized acid =
Concentration of undissociated acid = 0.497 M
Percent dissociated = 3.2 x