Understanding the Concepts

* HCl is a strong acid: This means it completely ionizes (dissociates) in water, releasing all of its hydrogen ions (H+).

* pH: A measure of the acidity or alkalinity of a solution. It is calculated using the following equation:

pH = -log[H+]

Calculation

1. Determine the [H+] concentration: Since HCl is a strong acid, the concentration of H+ ions will be equal to the concentration of the HCl solution:

[H+] = 0.280 M

2. Calculate the pH:

pH = -log(0.280)

pH ≈ 0.553

Answer: The pH of a 0.280 M HCl solution is approximately 0.553.