■ Class 10 Science Detailed Notes ■
Chapter 1: Chemical Reactions and Equations
■ Chemical Reaction:
A chemical reaction is a process in which one or more substances (reactants) are
converted into new substances (products) with different properties.
■ Characteristics of Chemical Reactions:
1 Change in state
2 Change in colour
3 Evolution of gas
4 Change in temperature
5 Formation of precipitate
■ Chemical Equation:
It is the symbolic representation of a chemical reaction using chemical formulas.
Example: Mg + O■ → MgO
■ Balanced Chemical Equation:
A chemical equation in which number of atoms of each element is same on both sides.
Example: 2Mg + O■ → 2MgO
■ Types of Chemical Reactions:
1 Combination Reaction: Two or more substances combine to form a single product.
Example: CaO + H■O → Ca(OH)■
2 Decomposition Reaction: A compound breaks into simpler substances. Example:
CaCO■ → CaO + CO■
3 Displacement Reaction: A more reactive element displaces a less reactive one.
Example: Zn + CuSO■ → ZnSO■ + Cu
4 Double Displacement Reaction: Exchange of ions between compounds. Example:
AgNO■ + NaCl → AgCl + NaNO■
■ Oxidation and Reduction:
Oxidation is gain of oxygen or loss of hydrogen. Reduction is loss of oxygen or gain of
hydrogen. These reactions occur together and are called redox reactions.
Chapter 1: Chemical Reactions and Equations
■ Chemical Reaction:
A chemical reaction is a process in which one or more substances (reactants) are
converted into new substances (products) with different properties.
■ Characteristics of Chemical Reactions:
1 Change in state
2 Change in colour
3 Evolution of gas
4 Change in temperature
5 Formation of precipitate
■ Chemical Equation:
It is the symbolic representation of a chemical reaction using chemical formulas.
Example: Mg + O■ → MgO
■ Balanced Chemical Equation:
A chemical equation in which number of atoms of each element is same on both sides.
Example: 2Mg + O■ → 2MgO
■ Types of Chemical Reactions:
1 Combination Reaction: Two or more substances combine to form a single product.
Example: CaO + H■O → Ca(OH)■
2 Decomposition Reaction: A compound breaks into simpler substances. Example:
CaCO■ → CaO + CO■
3 Displacement Reaction: A more reactive element displaces a less reactive one.
Example: Zn + CuSO■ → ZnSO■ + Cu
4 Double Displacement Reaction: Exchange of ions between compounds. Example:
AgNO■ + NaCl → AgCl + NaNO■
■ Oxidation and Reduction:
Oxidation is gain of oxygen or loss of hydrogen. Reduction is loss of oxygen or gain of
hydrogen. These reactions occur together and are called redox reactions.
