Class 10 Science Chapter 1 Notes
Chemical Reactions and Equations
This chapter explains chemical reactions, how to write chemical equations, types of reactions, and important concepts
like oxidation and reduction.
1. Chemical Reaction
A process in which one or more substances change into new substances with different properties.
Indicators of a Chemical Reaction
• Change in colour
• Evolution of gas
• Change in temperature
• Formation of precipitate
2. Chemical Equations
A symbolic representation of a chemical reaction using chemical formulas.
Balanced Chemical Equation
An equation in which the number of atoms of each element is equal on both sides.
3. Types of Chemical Reactions
Combination Reaction: Two or more substances combine to form one product.
Example: CaO + H■O → Ca(OH)■
Decomposition Reaction: A compound breaks into simpler substances.
Example: 2Pb(NO■)■ → 2PbO + 4NO■ + O■
Displacement Reaction: A more reactive element displaces a less reactive one.
Example: Zn + CuSO■ → ZnSO■ + Cu
Double Displacement Reaction: Exchange of ions between compounds.
Example: Na■SO■ + BaCl■ → BaSO■ + 2NaCl
4. Oxidation and Reduction
Oxidation: Addition of oxygen or removal of hydrogen.
Reduction: Removal of oxygen or addition of hydrogen.
Example: CuO + H■ → Cu + H■O
Chemical Reactions and Equations
This chapter explains chemical reactions, how to write chemical equations, types of reactions, and important concepts
like oxidation and reduction.
1. Chemical Reaction
A process in which one or more substances change into new substances with different properties.
Indicators of a Chemical Reaction
• Change in colour
• Evolution of gas
• Change in temperature
• Formation of precipitate
2. Chemical Equations
A symbolic representation of a chemical reaction using chemical formulas.
Balanced Chemical Equation
An equation in which the number of atoms of each element is equal on both sides.
3. Types of Chemical Reactions
Combination Reaction: Two or more substances combine to form one product.
Example: CaO + H■O → Ca(OH)■
Decomposition Reaction: A compound breaks into simpler substances.
Example: 2Pb(NO■)■ → 2PbO + 4NO■ + O■
Displacement Reaction: A more reactive element displaces a less reactive one.
Example: Zn + CuSO■ → ZnSO■ + Cu
Double Displacement Reaction: Exchange of ions between compounds.
Example: Na■SO■ + BaCl■ → BaSO■ + 2NaCl
4. Oxidation and Reduction
Oxidation: Addition of oxygen or removal of hydrogen.
Reduction: Removal of oxygen or addition of hydrogen.
Example: CuO + H■ → Cu + H■O
