Question

A solution is prepared by placing 29.0 g of KCl in a 0.700 L volumetric flask and adding water to dissolve the solid, then filling the flask to the mark. What is the molarity of an AgNO₃ solution if 39.4 mL of the KCl solution react exactly with 48.0 mL of the AgNO₃ solution?

Answer 1

KCl + AgNO₃ AgCl + KNO₃

1 mole of KCl reacts with 1 mole of AgNO₃

Molecular weight of KCl = 74.5 g/mol

Molarity of KCl = mass/(molecular weight Volume in litres)

Molarity of KCl = 29.0/(74.5 0.700) = 0.556 M

39.4 mL of KCl reacts with 48.0 mL of AgNO₃

No. of moles of KCl = M V = 0.556 0.0394 = 0.0219 mol

Since 1 mole of KCl reacts with 1 mole of AgNO₃

0.0219 mole of KCl will react with 0.0219 mole of AgNO₃

Molarity of AgNO₃ = n/V = 0.0219/0.048 = 0.456 M