Final answer:
The degree of ionization of propanoic acid cannot be directly calculated without additional information on the concentration of the acid in the solution.
Step-by-step explanation:
The degree of ionization of an acid is the fraction of its molecules that ionize when dissolved in water. For propanoic acid, with an ionization constant (Ka) of 1.32 × 10⁻⁵, the degree of ionization can be calculated under the assumption of a sufficiently dilute solution. The degree of ionization (α) is defined as the concentration of ionized acid divided by the initial concentration of the acid. However, without additional information such as the concentration of the acid in solution, we cannot directly calculate the degree of ionization for propanoic acid. Typically, the degree of ionization is calculated using the expression α = √(Ka ÷ C), where C is the molarity of the acid. To proceed with the calculation, the concentration (C) of the acid must be provided.