Question

What is the pH of a \( 0.01 \, \text{M} \) solution of hydrochloric acid (\( \text{HCl} \))?

• A. \( 1.0 \)
• B. \( 2.0 \)
• C. \( 0.5 \)
• D. \( 3.0 \)

Hint:

For strong acids, the concentration of hydrogen ions is equal to the concentration of the acid itself. Use \( \text{pH} = -\log [\text{H}^+] \) to calculate the pH.

Answer 1

The Correct Option is A

The pH of a strong acid like \( \text{HCl} \) is calculated using the formula: \[ \text{pH} = -\log [\text{H}^+] \] Since \( \text{HCl} \) dissociates completely in water, the concentration of hydrogen ions \( [\text{H}^+] \) is equal to the concentration of the acid, which is \( 0.01 \, \text{M} \). Substitute the value into the equation: \[ \text{pH} = -\log (0.01) = -(-2) = 2.0 \] Thus, the pH of the solution is \( 2.0 \).