Question

Which of these substances/ions can act as reducing agents?

1. Cd²⁺          

2. ClO^-                            

3. H₂O₂  

4. Cr₂O₇^2-

5. Al

Answer 1

A reducting agent, is an agent that have the ability to reduct another element with the gain of electrons to that element, and losing electrons of it's own (oxidating).

Wit this said, the only way to know which element can act as a reducting agent is to look all the ions or substances, and see it's oxidation state. If this state can be oxidated to a high value, then it can be a reducting agent. Let's see each of them:

Cd²⁺: would need to pass to a oxidation state higher than 2+. Cd only have that state, so it can't be a reducting agent.

ClO^-: In this, the Cl has a oxidation state of 1+. Cl can be in 1+, 3+, 5+ or 7+ as oxidation states, so this can act as a reducting agent.

H₂O₂ has the Oxigen with -1. It's a peroxide. In this uncommon oxidation state, the oxigen can pass from -1 to -2, or even, to 0. So it can act as an oxidating and reducting agent.

Cr₂O₇^2-: In this, Cr has the oxidation state of 6+, and the only thing it can do it's to be reducted to 3+ or 2+, so this acts as an oxidating agent and not a reducting agent.

Al: in this state, it has the oxidation state of 0, and still can be oxidated to 3+, so It can act as a reducting agent.

In conclusion, the ClO^-, H₂O₂ and Al can be reducting agents.