What is the pH of a 0.001 M aqueous solution of hydrochloric acid (HCl) at 25 degrees Celsius?
Answer and explanation
Correct answer: D. 3.0
- Step 1: HCl is a strong monoprotic acid that dissociates completely in water: HCl -> H+ + Cl-.
- Step 2: Therefore, [H+] = 0.001 M = 1.0 * 10^-3 M.
- Step 3: Use the pH definition: pH = -log10[H+] = -log10(1.0 * 10^-3) = 3.0.
Answer
3.0.
Why not the others: '1.0' corresponds to 0.1 M HCl; '11.0' represents pOH or a basic solution; '7.0' is neutral water.
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