Chapter 1: Chemical Reactions and Equations (Part 1) SSLC | Class 10
- Apr 10
- 2 min read
Understanding Chemical Reactions and Equations is one of the most important concepts in Class 10 Science. This chapter forms the foundation for advanced chemistry and helps students clearly understand how substances interact and transform into new products.
In this blog, we provide simple, easy-to-understand notes for Chemical Reactions and Equations (Part 1), along with examples, definitions, and important exam questions. These notes are designed to help students quickly revise key concepts and score better in exams.
Watch the Video Explanation
Meaning of Chemical Reaction
A chemical reaction is a process in which substances undergo a change to form new substances with different properties.
👉 Example:Burning paper produces ash (a new substance).
Types of Changes
🔹 Physical Change
No new substance is formed
Only physical properties (size, shape, state) change
👉 Example:
Tearing of paper
Cutting vegetables
🔹 Chemical Change
New substance is formed
Change is usually irreversible
👉 Example:
Burning of paper → Ash
Rusting of iron
Chemical Equation
A chemical equation represents a chemical reaction using symbols and formulas.
✍️ Example:
Word Equation:Magnesium + Oxygen → Magnesium oxide
Symbolic Equation:Mg + O₂ → MgO
Balanced vs Unbalanced Equation
🔹 Unbalanced Equation
Number of atoms on LHS ≠ RHS
🔹 Balanced Equation
Number of atoms on both sides are equal
👉 This follows the Law of Conservation of Mass
Why Balance Chemical Equations?
Chemical equations must be balanced:
To obey the Law of Conservation of Mass
Matter is neither created nor destroyed
Important Questions (Exam Focus)
Q1. What is a balanced chemical equation?
👉 Answer:An equation in which the number of atoms of each element is equal on both sides (reactants and products).
Q2. Why should chemical equations be balanced?
👉 Answer:To satisfy the Law of Conservation of Mass, which states that mass is neither created nor destroyed.
Q3.Examples of Balancing
Example 1:
Fe + H₂O → Fe₃O₄ + H₂
Balanced:3Fe + 4H₂O → Fe₃O₄ + 4H₂
Example 2:
BaCl₂ + H₂SO₄ → BaSO₄ + HCl
Balanced:BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
Example 3:
BaCl₂ + Al₂(SO₄)₃ → AlCl₃ + BaSO₄
Balanced:3BaCl₂ + Al₂(SO₄)₃ → 2AlCl₃ + 3BaSO₄
Comments