Chapter 12:Redox reactions

Redox reaction

• Redox reactions are reactions that involves both Reduction & Oxidation simultaneously.
• Transfer of oxygen from one substance to another
• Transfer of hydrogen from one substance to another
• Transfer of electrons from one substance to another
• Change in the oxidation states of the elements.

Oxidation

• [ ] When a substance gains oxygen in a chemical reaction, we say it has been oxidised. The reaction is called OXIDATION.

• Gain of oxygen

• Loss of electrons

• Increase in oxidation state

• Release electrons to the surroundings

• Gain in positive charge

• Occurs in reducing agents

Reduction

• [ ] When a substance gains hydrogen in a chemical reaction, we say it has been reduced. The reaction is called Reduction.

• gain of hydrogen

• Gain of electrons

• Oxidation state decreases

• Obtain electrons from the surroundings

• Gain of negative charge

• Occurs in oxidizing agents

Oxidizing agent

• [ ] An oxidizing agent is a substance that causes oxidation by accepting electrons; therefore, it gets reduced eg;

• halogens, potassium nitrate, and nitric acid.

Reducing agent

• [ ] A substance that tends to bring about reduction by being oxidized and losing electrons
• [ ] Earth metals, formic acid, oxalic acid, and sulfite compounds

Test for oxidizing agents

• Add Potassium iodide, if it changes from colourless to brown then Present.

Test for reducing agents

• Add acidified Potassium dichromate, if it changes from orange to green then present.