ChemistryScalar QuantityNCTB রসায়ন অধ্যায় ৮ (রসায়ন ও শক্তি)
Enthalpy Change
Bengali: বিক্রিয়া তাপ ও এনথালপি•Pronunciation: এনথালপি ডেল্টা এইচ•Symbol: \Delta H
Standard Definition:
The total heat energy absorbed or released during a chemical transformation under constant pressure conditions.
📐 Mathematical Equation, Units & Dimensions
Defining Mathematical Equation
Standard SI Unit
kJ/mol($kJ/mol$ (কিলোজুল/মোল))
Dimensional Analysis
CGS Unit
kcal/mol
📖 Physical Concept & Comprehensive Explanation
Enthalpy change measures net bond energetics. Bond breaking absorbs energy (+), whereas bond creation releases energy (-). Exothermic reactions show Delta H < 0 (warming the surroundings); endothermic reactions show Delta H > 0.
🎯 High-Yield Revision Points
- ✓Exothermic reactions: Delta H < 0 (releases heat).
- ✓Endothermic reactions: Delta H > 0 (absorbs heat).
- ✓Calculated via bond energies: Delta H = Broken bonds - Formed bonds.
Use Online Solver for Enthalpy Change
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❓ Frequently Asked Exam Questions (FAQ)
Common questions in board and competitive entrance examinations
Q1: Define exothermic and endothermic reactions.
Exothermic reactions release thermal energy (Delta H < 0), while endothermic reactions absorb heat (Delta H > 0).