Question

Answer the following questions.

(a) Name the different types of chemical reaction.

(b) Explain the difference between a combination and dissociation reaction.

(c) Explain with examples what is meant by oxidation.

(d) Explain with examples what is meant by reduction.

(e) What is a catalyst?

(f) On what factors does the speed of chemical reactions depend?

Answer 1

(a) The different types of chemical reactions are:

(i) Combination reaction

(ii) Decomposition reaction

(iii) Displacement reaction

(iv) Oxidation and reduction reaction

(b) Difference between combination and dissociation reaction:

Basis of difference		Combination reaction		Dissociation reaction
Definition		A chemical reaction in which a single compound is formed from two or more reactants is called combination reaction.		A chemical reaction in which a substance is broken down into two or more substances is called decomposition reaction.
Example

(c) Oxidation: The process in which oxygen combines with an element or when hydrogen is lost from a compound is termed as oxidation, and the chemical reaction in which this process takes place is termed as oxidation reaction.

Example:

(d) Reduction: The process in which hydrogen combines with an element or when oxygen is lost from a compound is termed as reduction, and the chemical reaction in which this process takes place is termed as reduction reaction.

Example:

(e) A substance that does not take part in chemical reaction but, which changes the speed of chemical reaction is called a catalyst.

Example: Raney nickel is used as catalyst in the reduction of vegetable oil.

(f) The speed of chemical reactions depends on the following factors:

(i) Size of reactant particles

(ii) Temperature

(iii) Concentration of reactant

(iv) Presence of catalyst