Chemistry- Acid/Base Chapter

Question

Calculate the pH of a solution made by mixing 10.8 mL of 4.7 x 10-2 M Ca(OH)2 with 23.6 mL of 0.10 M HCl. Assume that the volumes of the solutions are additive.

Answer 1

this is a strong acid strong base reactions . The pH will be determined by the excess of either acid or base after reaction.

mmoles of Ca(OH)2 = 0.5076 mmoles  = 2 X 0.5076mmoles of OH^-1

= 1.015 mmoles OH^-1

mmoles of HCl = 23.6 mL x 0.1 M = 2.36  so thr reaction will be

2.36 mmoles of H+ reacts with 1.015 mmoles of OH^-1 to leave 1.345 mmoles of H+ in a total of 34.4 mL    M = mmoles /mL = 0.039 M

pH = -log 0.039M H+ = 1.41