(HANDOUT) IGCSE Chemistry-Redox Reactions
REDOX REACTIONS
- Redox stands for reduction oxidation.
- Redox reaction, also called oxidation reduction reaction, is a chemical reaction in which one substance is reduced and another is oxidised simultaneously.
- Oxidation and reduction of substances occur simultaneously. As one substance is reduced the other is oxidised.
- An oxidising agent is a substance that causes the oxidation of the other substance. Therefore, the substance that is reduced in a reaction is the oxidising agent.
- A reducing agent is a substance that causes the reduction of the other substance. For example, the substance that is oxidised in a reaction is the reducing agent.
OXYGEN IN REDOX REACTION
- Oxidation is the gain of oxygen by the substance. A substance that has gained oxygen is said to be oxidised.
- Reduction is the loss of oxygen by the substance. A substance that has lost oxygen is said to be reduced.
HYDROGEN IN REDOX REACTION
- Oxidation is the loss of hydrogen by the substance. A substance that has lost hydrogen is said to be oxidised.
- Reduction is the gain of hydrogen by the substance. A substance that has gained hydrogen is said to be reduced.
ELECTRONS IN REDOX
- Oxidation is the loss of electrons. A substance that loses electrons is oxidised.
- Reduction is the gain of electrons. A substance that gains electrons is reduced.
- The reaction below shows a redox reaction involving the gain and loss of electrons.
OXIDATION NUMBER
- Oxidation number, also called oxidation state, is the number of electrons an atom gains or losses in a chemical combination.
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