Phosphoric acid h3po4 is an important industrial chemical used in fertilizers, detergents, and the food industry. it is produced by two different methods. In the electric furnace method elemental phosphorus P4 is in air to form P4O10, which is then combined with water to give H3PO4. In the wet process the mineral phosphate rock Ca5(PO4)3F is combined with sulfuric acid to give H3PO4 and HF and CaSO4.

Write equations for these processes, and classify each step as preciptation, acid-base, or redox reaction

1)   P₄ + 5O₂ → P₄O₁₀  redox reaction

2)   P₄O₁₀ + 6H₂O → 4H₃PO₄  acid-base reaction

3)   Ca₅(PO₄)₃F + 5H₂SO₄ → 3H₃PO₄ + HF + 5CaSO₄  precipitation reaction

Explanation:

The reactions that take place in the electric furnace method are:

1)   P₄ + 5O₂ → P₄O₁₀

This is a redox reaction, because the oxidation state of the reactants is changed.

2)   P₄O₁₀ + 6H₂O → 4H₃PO₄

This is an acid-base reaction, because there's an exchange of H⁺ species.

The reaction that takes place in the wet process is:

3)   Ca₅(PO₄)₃F + 5H₂SO₄ → 3H₃PO₄ + HF + 5CaSO₄

This is an precipitation reaction, because a precipitate (a solid phase in a liquid phase) is formed.

the answer is c.the valence of the atoms combine .