Class 10 Science - Chapter 1
Chemical Reactions and Equations (Topper Notes)
1. Chemical Reaction
A chemical reaction is a process in which reactants undergo a chemical change to form new
substances (products) with different properties.
2. Characteristics of Chemical Reactions
1Change in colour
2Change in temperature (heat/light)
3Formation of gas
4Formation of precipitate (insoluble solid)
5Change in state
3. Chemical Equations
Word Equation: Magnesium + Oxygen → Magnesium Oxide
Balanced Equation: 2Mg(s) + O■(g) → 2MgO(s)
4. Law of Conservation of Mass
Mass is neither created nor destroyed in a chemical reaction. Total mass of reactants = total mass
of products.
5. Types of Chemical Reactions
Combination: CaO + H■O → Ca(OH)■
Decomposition: CaCO■(s) → CaO(s) + CO■(g)
Displacement: Fe(s) + CuSO■(aq) → FeSO■(aq) + Cu(s)
Double Displacement: Na■SO■ + BaCl■ → BaSO■↓ + 2NaCl
6. Oxidation and Reduction
