exothermic reaction

 Here’s a clear, student-friendly explanation of the concept of Exothermic Reactions, as seen in Activity 1.4, with examples and a follow-up on the type of reaction in Activity 1.1, aligned to CBSE Class 10 Science standards.

🔥 Exothermic Chemical Reactions

(From Chapter 1 – Chemical Reactions and Equations)

🎯 What is an Exothermic Reaction?

A chemical reaction in which heat is released along with the formation of products is called an exothermic reaction.

✅ These reactions often make the surroundings warm or hot.

🧪 Activity 1.4 Observation:

When calcium oxide (quick lime) reacts with water, the beaker becomes hot. This is because a large amount of heat is released.

📘 Chemical Equation:

CaO (s)+H2O (l)→Ca(OH)2(aq)+Heat\text{CaO (s)} + \text{H}_2\text{O (l)} \rightarrow \text{Ca(OH)}_2 (aq) + \text{Heat}

✅ This is both a combination and an exothermic reaction.

🔥 Other Common Exothermic Reactions:

✅ (i) Burning of Natural Gas (Methane)

CH4(g)+2O2(g)→CO2(g)+2H2O (g)+Heat\text{CH}_4 (g) + 2\text{O}_2 (g) \rightarrow \text{CO}_2 (g) + 2\text{H}_2\text{O (g)} + \text{Heat}

Used in cooking and fuel-based heaters.

✅ (ii) Respiration in Our Body

Food (especially carbohydrates like rice, potatoes, bread) is broken down into glucose. This glucose reacts with oxygen in cells to release energy.

C6H12O6(aq)+6O2(aq)→6CO2(aq)+6H2O (l)+Energy\text{C}_6\text{H}_{12}\text{O}_6 (aq) + 6\text{O}_2 (aq) \rightarrow 6\text{CO}_2 (aq) + 6\text{H}_2\text{O (l)} + \text{Energy}

✅ Respiration is a biological exothermic reaction.

✅ (iii) Composting of Vegetable Waste

When vegetable matter decomposes, heat is released, making the compost pile warm.

🔍 Question:

Identify the type of reaction taking place in Activity 1.1 (burning of magnesium).

✅ Answer:

  • Type: Combination Reaction (Mg + O₂ → MgO)

  • Also an Exothermic Reaction (gives off light and heat)

🧠 Quick Summary Table:

Reaction Type
CaO + H₂O → Ca(OH)₂ + Heat Combination + Exothermic
CH₄ + O₂ → CO₂ + H₂O + Heat Combustion + Exothermic
Glucose + O₂ → CO₂ + H₂O + E Biological + Exothermic (Respiration)
Burning of Mg Combination + Exothermic

🎤 Final Thought for Students:

“Reactions that release energy — whether in your body, a stove, or a compost pile — are all part of the science that keeps life and the planet running warm.”

Would you like a concept map, quiz, or visual animation on exothermic vs. endothermic reactions for deeper engagement?


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