How can the degree of ionization of a weak acid be determined?

The degree of ionization of a weak acid can be determined by comparing the concentration of undissociated acid with its initial concentration. This method involves measuring how much of the acid has dissociated into its ions in solution.

For example, if you start with a known initial concentration of a weak acid and you measure the concentration of the undissociated acid at equilibrium, you can then compute the amount of acid that has ionized. The degree of ionization is expressed as a fraction or percentage of the initial concentration that has formed ions. This provides a clear quantitative measure of the acid's ionization in aqueous solution.

In contrast, measuring the temperature change during dissociation is not a reliable method for determining degree of ionization, as temperature changes could result from various factors unrelated to the extent of ionization. Calculating pressure change during the reaction is also not applicable for weak acids in liquid solutions, as this approach is more suited to gas-phase reactions or processes where gas production is significant. Observing the color change of a pH indicator may provide an indication of the acid's strength and the solution's pH, but it doesn’t quantitatively measure the extent of ionization, making it less effective for this purpose.