Class 10 Science – Sample Notes
Chapter: Chemical Reactions and Equations
(CBSE / Common Board)
1. What is a Chemical Reaction?
A chemical reaction is a process in which one or more substances (reactants) change into new
substances (products) with different properties.
Signs of a chemical reaction:
Change in colour
Formation of gas (bubbles)
Change in temperature (hot or cold)
Formation of precipitate (solid)
Change in smell
2. Chemical Equations
A chemical equation is a short way to write a chemical reaction using symbols and formulae.
Example:
Magnesium + Oxygen → Magnesium oxide
Mg + O₂ → MgO
3. Balancing Chemical Equations
The number of atoms of each element must be the same on both sides.
Example:
Unbalanced: H₂ + O₂ → H₂O
Balanced: 2H₂ + O₂ → 2H₂O
4. Types of Chemical Reactions
Type of Reaction
Explanation
Example
Chapter: Chemical Reactions and Equations
(CBSE / Common Board)
1. What is a Chemical Reaction?
A chemical reaction is a process in which one or more substances (reactants) change into new
substances (products) with different properties.
Signs of a chemical reaction:
Change in colour
Formation of gas (bubbles)
Change in temperature (hot or cold)
Formation of precipitate (solid)
Change in smell
2. Chemical Equations
A chemical equation is a short way to write a chemical reaction using symbols and formulae.
Example:
Magnesium + Oxygen → Magnesium oxide
Mg + O₂ → MgO
3. Balancing Chemical Equations
The number of atoms of each element must be the same on both sides.
Example:
Unbalanced: H₂ + O₂ → H₂O
Balanced: 2H₂ + O₂ → 2H₂O
4. Types of Chemical Reactions
Type of Reaction
Explanation
Example
