Answer to Question #316509 in General Chemistry for Autumn123

Question

Calculate the volume of 0.400 M H3PO4 needed to react with 200.0 mL of 0.200 M NaOH.

Answer 1

Solution:

Balanced chemical equation:

H₃PO₄ + 3NaOH ⟶ Na₃PO₄ + 3H₂O

According to stoichiometry:

Moles of H₃PO₄ = Moles of NaOH / 3

or

3 × Molarity of H₃PO₄ × Volume of H₃PO₄ = Molarity of NaOH × Volume of NaOH

Therefore,

Volume of H₃PO₄ = (Molarity of NaOH × Volume of NaOH) / (3 × Molarity of H₃PO₄)

Volume of H₃PO₄ = (0.200 M × 200.0 mL) / (3 × 0.400 M) = 33.3 mL

Volume of H₃PO₄ = 33.3 mL

Answer: 33.3 mL of H₃PO₄ needed