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Science & Math for K6 - K12 Students


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Redox Reactions

How fireworks work? How fireworks work? Fireworks have been a traditional part of festive celebrations since they were invented by Chinese thousands of years ago. The chemical reactions that take place in firecrackers are REDOX reactions. Firecrackers consist of gunpowder, oxidants such as potassium nitrate (KNO3) and potassium chlorate (KClO4), reductants such as charcoal, sulfur etc., and metals such as Cr, Fe, Al etc., (to get colored sparkles). Here KNO3 and KClO4 oxidizes sulfur, carbon (charcoal) and metal ions with evolution of heat, sound and light.

Learning Objectives

After completing the topic, the student will be able to:

  • Define oxidation and reduction reactions.
  • Represent a redox reaction in terms of electron transfer.
  • Define oxidizing and reducing agents and give examples.
  • Identify the oxidizing or reducing agent in a given reaction.
  • Define oxidation number and calculate the change in valency or oxidation number of species in a redox reaction.
  • Balance a redox reaction using ion–electron method.
  • Discuss everyday examples those involved a redox process.
Simple understanding of oxidation and reduction reactions Simple understanding of oxidation and reduction reactions Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons.
Oxidation and Reduction Reactions

In chemical reactions, inter molecular bonds between reactants are broken and new bonds are made in the product molecules. This transformation is the simple rearrangement of electrons.

Reactions that involve the transfer of one or more electrons from one reactant to another are called oxidation–reduction reactions.

Oxidation is the process in which electrons are removed from an atom or ion.
Reduction involves the addition of electrons to an atom or ion.

Simple meaning of oxidation reaction would be an addition of oxygen to a substance. Reduction reaction would mean removal of oxygen from a substance.

Burning of coal is an oxidation process Burning of coal is an oxidation process Oxidation, any chemical reaction in which an atom of an element loses one or more of its electrons to an atom of a different element. Familiar examples of oxidation include the burning of coal, which is rapid oxidation and the rusting of iron, which is slow oxidation.
Examples for oxidation process

Since years, we have been burning coal to get heat. We also know that for burning of coal we need supply of fresh air. What happens when coal burns? The oxygen from the air is necessary for the process of burning. We can represent this reaction by the chemical equation as follows:

C + O2 CO2 (g)

Carbon dioxide is the product. If sufficient supply of fresh air is not available, the reaction may be as follows:

2C + O2 2CO(g)

Carbon monoxide is the product. The products of burning of coal, both CO2 and CO being gases escape in the atmosphere.

Another common experience is burning of magnesium wire, which is popular in the firework

2Mg + O2 2MgO
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