Understanding the Concepts

* HCl is a strong acid: This means it completely ionizes in water, meaning all of the HCl molecules break apart into H⁺ ions and Cl⁻ ions.

* pH is a measure of acidity: The lower the pH, the more acidic the solution. The pH scale ranges from 0 to 14, with 7 being neutral.

Calculations

1. Find the concentration of H⁺ ions: Since HCl is a strong acid, the concentration of H⁺ ions is equal to the initial concentration of HCl:

[H⁺] = 4.3 x 10⁻² M

2. Use the pH formula:

pH = -log[H⁺]

3. Plug in the value and calculate:

pH = -log(4.3 x 10⁻²)

pH ≈ 1.37

Therefore, the pH of a 4.3 x 10⁻² M HCl solution is approximately 1.37.