Question

(a) What is a chemical reaction ?

(b) State the conditions necessary for a chemical change or reaction.

Answer 1

(a) A process that involves rearrangement of the molecular or ionic structure of a substance, as distinct from a change in physical form or a nuclear reaction. Key Concepts:

• A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does.
• In a chemical reaction, the atoms and molecules that interact with each other are called reactants.
• In a chemical reaction, the atoms and molecules produced by the reaction are called products.
• In a chemical reaction, only the atoms present in the reactants can end up in the products. No new atoms are created, and no atoms are destroyed.
• In a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.

(b) Conditions necessary for a chemical change or reaction:
1. Presence of a sufficient amount of energy in form of heat electricity effect or light or in form of catalysts.

2. The particle of reactants must collide with each other with correct angle to break bond for forming new substances