Question

The compound p4s3 is oxidized by nitrate ions in acid solution to give phosphoric acid, sulfate ions, and nitric oxide no. what is the coefficient of h3po4 in the balanced equation for the reaction?

Answer 1

Answer is: the coefficient of phosphoric acid is 12.
Chemical reaction: P₄S₃ + NO₃⁻ + H⁺ → H₃PO₄ + SO₄⁻ + NO.
Reduction half reaction: NO₃⁻ + 4H⁺ + 3e⁻ → NO + 2H₂O /·38
Oxidation half reaction: P₄S₃ + 28H₂O → 4H₃PO₄ + 3SO₄²⁻ + 44H⁺ + 38e⁻ /·3.
38NO₃⁻ + 152H⁺ + 3P₄S₃ + 84H₂O → 38NO + 76H₂O + 12H₃PO₄ + 9SO₄²⁻ + 132H⁺.
Balnced chemical reaction:
3P₄S₃ + 38NO₃⁻ + 20H⁺ + 8H₂O → 12H₃PO₄ + 9SO₄²⁻ + 38NO.

Answer 2

The answer correct answer is 12.
The coefficient of H3PO4 is 12. The balanced chemical equation for the reaction is; 3P₄S₃ + 38NO₃⁻ + 20H⁺ + 8H₂O → 12H₃PO₄ + 9SO₄²⁻ + 38NO; The reaction is a redox reaction; where some elements undergo oxidation (loss of electrons) while the other undergo reduction (gaining of electrons). The half reaction for the reduction is; NO3- + 4H+ + 3e---> NO + 2H2O, while the oxidation half reaction is; P4S3 + 28 H2O --> H3PO4 + 3SO42- + 4H+ + 38 e-; To obtain a complete and balanced equation; we then multiply by the coefficients such that the electrons on both sides cancel and add the half reactions together. which eventually gives us; 3P₄S₃ + 38NO₃⁻ + 20H⁺ + 8H₂O → 12H₃PO₄ + 9SO₄²⁻ + 38NO