Final answer:
To determine the pH of the given acid solution, use the formula pH = -log[H+]. Assume the concentration of the acid is equal to the concentration of the conjugate base. Calculate the concentration of [H+] using the given Ka value and the concentration of the acid. Plug the [H+] value into the pH formula to find the pH.
Step-by-step explanation:
The pH of a solution can be determined using the formula pH = -log[H+]. In this case, we are given the concentration of the acid solution, which is 0.28 M. To find the pH, we need to calculate the concentration of the hydrogen ion ([H+]).
Since the acid is a weak acid, we can assume that the concentration of the acid ([HC7H5O2]) is equal to the concentration of the conjugate base ([C7H5O2-]). Using the given Ka value (6.3 × 10^-5), we can calculate the concentration of [H+] using the formula:
[H+] = sqrt((Ka * [HC7H5O2])
Once we find the [H+], we can plug it into the pH formula: pH = -log[H+].