Question

(a) Find out the oxidising agent and reducing agent in the following reaction: 

Cu(s) + 2Ag²⁺ (aq) → Cu²⁺ (aq) + 2Ag(s) 

(b) Balance the following redox reaction in acid medium using oxidation number method. 

Cr₂O₇^2- + Fe²⁺ → Cr³⁺ + Fe³⁺

Answer 1

1. Oxidising agent – Ag 

Reducing Agent – Cu

2. Assigning oxidation number:

Calculate the increase and decrease in the oxidation number and make them equal:

Cr₂O₇^2- + Fe²⁺ → Cr³⁺ + Fe³⁺

Equating  the ionic charges:

Cr₂O₇^2- + 6Fe²⁺ +14H⁺ → 2Cr³⁺ + 6Fe³⁺

Balancing H and O :

Cr₂O₇^2- + 6Fe²⁺ +14H⁺  → 2Cr³⁺ + 6Fe³⁺ + 7H₂O