Answer to Question #268969 in General Chemistry for Vinne

Question

Consider the reaction: 3HNO3(aq) + K3PO4(aq)  H3PO4 + 3KNO3(aq) What is the concentration of an HNO3 solution if 25.0 mL reacts with 38.5 mL of 0.145 M K3PO4?

Answer 1

Solution:

Balanced chemical equation:

3HNO₃(aq) + K₃PO₄(aq) → H₃PO₄ + 3KNO₃(aq)

According to stoichiometry:

3 mol of HNO₃ reacts with 1 mol of K₃PO₄

Therefore,

Moles of HNO₃ = 3 × Moles of K₃PO₄

Moles = Molarity × Volume

Therefore,

Molarity of HNO₃ × Volume of HNO₃ = 3 × Molarity of K₃PO₄ × Volume of K₃PO₄

Molarity of HNO₃ × (25.0 mL) = 3 × (0.145 M) × (38.5 mL)

Molarity of HNO₃ = (3 × 0.145 M × 38.5 mL) / (25.0 mL) = 0.6699 M = 0.670 M

Molarity of HNO₃ = 0.670 M

Answer: The molar concentration of an HNO₃ solution is 0.670 M