Question

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

• A. 12
• B. 2
• C. 7
• D. 1

Hint:

Remember the relation pH plus pOH equals 14 at room temperature, connected through the ion product of water, Kw. For a strong acid like HCl, the hydrogen ion concentration is equal to the acid concentration itself.

Answer 1

The Correct Option is B

For hydrochloric acid (HCl), a strong acid, complete dissociation in water means the concentration of \( \text{H}^+ \) ions equals the acid's concentration, which is 0.01 M. The pH calculation formula is: \[ \text{pH} = -\log [\text{H}^+] \] Substituting \( [\text{H}^+] = 0.01 \) M yields: \[ \text{pH} = -\log (0.01) = 2 \] Therefore, the solution's pH is 2, corresponding to option (2).