Titration: Molarity of Acid/Base

Question

An aqueous solution of perchloric acid is standardized by titration with a 0.110 M solution of calcium hydroxide.

If 24.2 mL of base are required to neutralize 24.3 mL of the acid, what is the molarity of the perchloric acid solution?

_______M perchloric acid

Answer 1

Write the balanced equation for the titration:

2HClO4 + Ca(OH)2 ==> Ca(ClO4)2 + 2H2O

moles Ca(OH)2 used = 0.110 mol / L x 0.0242 L = 0.00266 moles Ca(OH)2 used

moles HClO4 present = 0.00266 mol Ca(OH)2 x 2 mol HClO4 / 1 mol Ca(OH)2 = 0.00532 mols HClO4 present

This is in 24.3 = 0.0243 L, so concentration of HClO4 is 0.00532 mols / 0.0243 L = 0.219 M