Question

Add oxidation numbers to the following reaction: 2 H3PO4 (aq) + 2 Cr(s) → 2 CrPO4 (aq) + 3 H2(g). Identify the atom that is oxidized and identify the oxidizing agent.

Answer 1

The atom that is oxidized : Cr

The oxidizing agent : H₃PO₄

Further explanation

Reaction

2 H₃PO₄ (aq) + 2Cr(s) → 2 CrPO₄ (aq) + 3H₂(g)

Atoms undergoing a reduction reaction (decrease in oxidation number) and an oxidation reaction (increase in oxidation number)

• Reduction (+1 to 0)

H⁺(in H₃PO₄) =+1

H₂=0

• Oxidation (0 to +3)

Cr = 0

Cr³⁺(in CrPO₄ )

the oxidizing agent.⇒which undergoes a reduction reaction and oxidizes another compound/element : H₃PO₄