Question

What happens when ortho phosphoric acid is heated to ${600}^{o}C$?

• A. Phosphorus is formed
• B. Phosphorus acid is formed
• C. Hydrogen gas is released
• D. Phosphorus pentaoxide is formed

Answer 1

The correct option is D Phosphorus pentaoxide is formed

phosphoric acid on heating to 316 degrees yields metaphosphoric acid

Reaction: $H_{3}P{O}_4\to HP{O}_3+H_{2}O$ (H3PO4 is a diprotic acid)

If we heat the phosphoric acid to 600 degrees we get phosphorus pentaoxide where condensation takes place along with dehydration.

Reaction: $2H_{3}P{O}_4\to P_2{O}_5+3H_{2}O$