The pH of a solution prepared by mixing 50.0 mL of 0.125 M NaOH and 40.0 mL of 0.125 M HNO₃ is ________. A)13.29 B)7.00 C)8.11 D)11.00 E)12.14

Question

Quizplus · Accepted Answer

The solution is a mixture of a strong base (NaOH) and a strong acid (HNO3). The moles of NaOH are 0.00625 (50.0 mL * 0.125 M) and the moles of HNO3 are 0.005 (40.0 mL * 0.125 M). The excess moles of NaOH are 0.00125. The total volume of the solution is 90.0 mL. The concentration of OH- is 0.00125 moles / 0.090 L = 0.01389 M. The pOH is -log(0.01389) = 1.857, and the pH is 14 - 1.857 = 12.14.

The PH of a Solution Prepared by Mixing 50