Suppose 16.84 mL of 0.465 M Ca(OH)2 is required to neutralize 18.4 mL of aqueous HCl solution. What is the molarity of the HCl solution?

Question

Suppose that 16.84 mL of 0.465 M Ca(OH)2

is required to neutralize 18.4 mL of aqueous

HCl solution. What is the molarity of the HCl

solution?

Answer in units of M.

Answer 1

Write the chemical equation for the reaction:

2HCl + Ca(OH)2 ---> CaCl2 + 2H2O

The 2:1 ratio between HCl and Ca(OH)2 will be used below.

millimoles Ca(OH)2 ---> (0.465 mmol/mL) (16.84 mL) = 7.8306 mmol

For every 1 mole of Ca(OH)2 neutralized, 2 moles of HCl are required. Therefore:

(7.8306 mmol) (2) = 15.6612 mmol of HCl

molarity HCl ---> 15.6612 mmol / 18.4 mL = 0.8512 M

Round off more, as you see fit.