Find the half way point data (pH and mL of added acid) for the titration of 50ml of .1M Ca(OH)2 with .5M HCl. Assume that calcium hydroxide is completely soluble at this concentration

Answer 1

add 10 mL of 0.5 M HCl to neutralize half of the base reaching the half-equivalence point.

pH will be 12.92

HCl: 10 mL x 0.5 mmol/ml = 5 mmol

Ca(OH)2: 50 mL x 0.1 mmol/ml x 2 OH/Ca(OH)2 = 10 mmol

remaining solution: 10 - 5 = 5 mmol OH- in 60 ml = 0.0833 M OH-

pOH = -log(0.0833) = 1.08

pH = 14 - pOH = 12.92