Question

What is the pH of a 0.01 M hydrochloric acid (HCl) solution?

• A. 2
• B. 4
• C. 7
• D. 12

Hint:

The pH of a strong acid solution can be directly calculated using the negative logarithm of its concentration since strong acids dissociate completely in water.

Answer 1

The Correct Option is A

Hydrochloric acid (HCl) is a strong acid and dissociates completely in water: \[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \] Therefore, the concentration of hydrogen ions \([H^+]\) is equal to the concentration of HCl, which is 0.01 M. The pH is calculated using the formula: \[ \text{pH} = -\log [H^+] \] Substituting the values: \[ \text{pH} = -\log (0.01) = 2 \] Thus, the pH of the solution is 2.