A 15.0 mL solution of Ba(OH)₂ is neutralized with 22.5 mL of 0.200 M HCl. What is the concentration of the original Ba(OH)₂ solution?

Answer 1

The neutralization reaction is given

Ba(OH)₂+HCl → Ba(Cl)₂ + H₂O

Balance by balancing chlorine and checking other elements are balanced.

Ba(OH)₂ + 2HCl → Ba(Cl)₂ + 2H₂O

Thus 2 moles of HCl are needed to neutralize 1 mole of Ba(OH).

Moles of HCl = 0.2 times 22.5/1000 = 0.0045 moles

This number of moles of HCl would neutralize 0.0045/2 = 0.00225 moles of Ba(OH)₂

Since 150ml =.015l of Ba(OH)₂ was used, the concentration is 0.00225/0.15 = 0.015M