What is the pH of an aqueous solution made by mixing 25.00 mL of 0.100 mol L^-¹ HCl with 40.00 mL of 0.100 mol L^-1 KOH?
Assume that the volumes of the solutions are additive.

Question

Quizplus · Accepted Answer

The reaction between HCl and KOH is a neutralization reaction, where HCl (a strong acid) reacts with KOH (a strong base) to form water and KCl (a salt). The moles of HCl are 25.00 mL * 0.100 mol/L = 2.5 mmol, and the moles of KOH are 40.00 mL * 0.100 mol/L = 4.0 mmol. Since KOH is in excess by 1.5 mmol (4.0 mmol - 2.5 mmol), the solution will be basic. The concentration of excess OH- is 1.5 mmol / (25.00 mL + 40.00 mL) = 1.5 mmol / 65.00 mL = 0.0231 mol/L. The pOH is -log(0.0231) ≈ 1.64, and since pH + pOH = 14, the pH is 14 - 1.64 = 12.36.

What Is the PH of an Aqueous Solution Made by Mixing