Question

explain the balancing of redox reaction by oxidation number method.

Answer 1

In the oxidation number change method the underlying principle is that the gain in the oxidation number (number of electrons) in one reactant must be equal to the loss in the oxidation number of the other reactant

Answer 2

Answer:

Two methods are used to balance chemical equation for redox processes: Oxidation number method and Half reaction method or Ion electron method.

(1) Oxidation number method:

Step 1 : Balance the given equation for all atoms except H and O. Identify the atoms undergoing change in oxidation number.

Step 2 : Show an increase in oxidation number for oxidised species and a decrease in oxidation number for reduced species. Balance total increase and decrease in oxidation numbers.

Step 3 : Balance O atoms by adding H_2O to the side deficient of O atoms and balance H atoms by adding H^+ ions to the side deficient of H atoms and they are finally removed by forming H_2O.

Step 4: In basic medium OH^-ions are added which are removed as H_2O.

Step 5: Check the equation with respect to number of atoms of each element on both the sides.

(2) Half reaction methods :

Step 1: Assign oxidation numbers to all atoms in the given reaction.

Step 2 : Divide the equation into two half equations, one for oxidation and the other for reduction.

Step 3: Find the loss of electrons and gain of electrons by atoms in the reaction.

Step 4: Balance the loss and gain of electrons.

Step 5: Add both the reactions.

Step 6: For acidic medium H^+ ions are added while for basic medium OH^- are added.