NCERT Class 10 Science
Comprehensive Study Notes: Chapter 1
Chapter 1: Chemical Reactions and Equations
A Chemical Reaction is a process where the reactant substances undergo chemical
changes to form new products with different properties.
1. Identifying a Chemical Reaction
A chemical reaction can be identified by any of the following observations:
• Change in state
• Change in color
• Evolution of a gas
• Change in temperature
2. Chemical Equations & Balancing
According to the Law of Conservation of Mass, mass can neither be created nor
destroyed in a chemical reaction. Therefore, the number of atoms of each element must
remain the same on both sides.
Example (Balanced):
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
3. Types of Chemical Reactions
General
Reaction Type Description
Formula
Two or more substances combine to form a
Combination A + B → AB
single product.
1
Comprehensive Study Notes: Chapter 1
Chapter 1: Chemical Reactions and Equations
A Chemical Reaction is a process where the reactant substances undergo chemical
changes to form new products with different properties.
1. Identifying a Chemical Reaction
A chemical reaction can be identified by any of the following observations:
• Change in state
• Change in color
• Evolution of a gas
• Change in temperature
2. Chemical Equations & Balancing
According to the Law of Conservation of Mass, mass can neither be created nor
destroyed in a chemical reaction. Therefore, the number of atoms of each element must
remain the same on both sides.
Example (Balanced):
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
3. Types of Chemical Reactions
General
Reaction Type Description
Formula
Two or more substances combine to form a
Combination A + B → AB
single product.
1
