What is the pH of a solution prepared by dissolving 0.0400 mol of a strong monoprotic acid HA in enough water to make 400.0 mL of solution? Assume complete dissociation.
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Correct answer
A. 1.00
Principle or equation
For a strong monoprotic acid, [H+] = initial acid concentration. pH = -log[H+]. Concentration = moles / volume in liters.
Why this answer is correct
Volume = 400.0 mL = 0.4000 L. [HA] = 0.0400 mol / 0.4000 L = 0.100 M. Since it is strong and monoprotic, [H+] = 0.100 M. pH = -log(0.100) = 1.00.
Example
pH = -log(0.100) = 1.00.
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