class 10 science chapter 1 chemical reactions and equation

 

Class 10 Science Chapter 1 Notes – Chemical Reactions and Equations

July 07, 2025

 

🔬 Chemical Reactions and Equations – Class 10 Notes

✅ Definition:

A chemical reaction is a process in which one or more substances (reactants) are converted into one or more new substances (products), usually with energy change.

💡 Characteristics of Chemical Reactions:

  1. Change in state

  2. Change in color

  3. Evolution of gas

  4. Change in temperature

  5. Formation of a precipitate

🔁 

Types of Chemical Reactions:

Type of ReactionExample
Combination ReactionCaO + H₂O → Ca(OH)₂
Decomposition Reaction2H₂O → 2H₂ + O₂
Displacement ReactionZn + CuSO₄ → ZnSO₄ + Cu
Double DisplacementNa₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
Oxidation & ReductionFe → Fe₂O₃ (Rusting of Iron)

⚖️ Balanced vs Unbalanced Equations:

Unbalanced:
H₂ + O₂ → H₂O ❌
Balanced:
2H₂ + O₂ → 2H₂O ✅

📜 Law of Conservation of Mass:

Mass can neither be created nor destroyed in a chemical reaction.
👉 Therefore, total mass of reactants = total mass of products

🧠 Important Terms:

  • Reactants: Substances that react

  • Products: New substances formed

  • Precipitate: Solid formed from two liquids

✍️ Key Reactions to Remember:

  1. Rusting: Fe + O₂ + H₂O → Fe₂O₃·xH₂O

  2. Burning of Mg ribbon: 2Mg + O₂ → 2MgO

  3. Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂  




Science Chapter notes




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