JAMB/WAEC Chemistry 2027 EP 116 - Enthalpy + Free JAMB/WAEC Past Questions & Answers

JAMB/WAEC Chemistry EP 116 - Enthalpy + Free JAMB/WAEC Past Questions & Answers In this lesson, we study Enthalpy, a key concept in Chemical Energetics that explains the heat content of a system and the energy changes that occur during chemical reactions. Understanding enthalpy is essential for solving questions on exothermic and endothermic reactions in JAMB, WAEC, NECO, and Post UTME Chemistry. Topics Covered • Enthalpy • Enthalpy Change (ΔH) • Exothermic Reactions • Endothermic Reactions • Heat of Reaction • Energy Profile What Is Enthalpy? Enthalpy (H) is the total heat content of a chemical system at constant pressure. Since the absolute value of enthalpy cannot be measured directly, chemists are mainly concerned with the change in enthalpy (ΔH) during a chemical reaction. What Is Enthalpy Change (ΔH)? Enthalpy change is the difference between the enthalpy of the products and the enthalpy of the reactants. ΔH = Enthalpy of Products − Enthalpy of Reactants Types of Enthalpy Change 1. Exothermic Reaction ✔ Heat is released to the surroundings. ✔ Products have lower energy than reactants. ✔ ΔH is negative. Examples: • Combustion of fuels • Neutralization reactions 2. Endothermic Reaction ✔ Heat is absorbed from the surroundings. ✔ Products have higher energy than reactants. ✔ ΔH is positive. Examples: • Photosynthesis • Thermal decomposition of calcium carbonate Importance of Enthalpy ✔ Explains energy changes in chemical reactions. ✔ Helps predict whether heat is absorbed or released. ✔ Important in industrial chemical processes. ✔ Forms the basis of thermochemistry calculations. Frequently Tested JAMB Areas 🔥 Enthalpy 🔥 Enthalpy Change (ΔH) 🔥 Exothermic Reactions 🔥 Endothermic Reactions 🔥 Heat of Reaction 🔥 Energy Changes Free JAMB/WAEC Past Questions & Answers 1. Enthalpy is the measure of a system's? A. Density B. Heat content C. Pressure D. Volume Answer: B 2. Enthalpy change is represented by the symbol? A. ΔT B. ΔP C. ΔH D. ΔV Answer: C 3. In an exothermic reaction, the value of ΔH is? A. Positive B. Negative C. Zero D. Infinite Answer: B 4. Which of the following is an endothermic reaction? A. Combustion of petrol B. Neutralization C. Photosynthesis D. Respiration Answer: C 5. In an endothermic reaction, the products have? A. Lower energy than the reactants B. Equal energy as the reactants C. Higher energy than the reactants D. No energy Answer: C Quick Revision Note ✔ Enthalpy (H) is the heat content of a system. ✔ Enthalpy change (ΔH) is the difference between the enthalpy of products and reactants. ✔ Exothermic reactions have a negative ΔH. ✔ Endothermic reactions have a positive ΔH. ✔ Energy is released in exothermic reactions and absorbed in endothermic reactions. This lesson is highly recommended for JAMB, WAEC, NECO, and Post UTME candidates preparing for Chemistry examinations. #JAMBChemistry #WAECChemistry #Enthalpy #ChemicalEnergetics #ExothermicReaction #EndothermicReaction #Thermochemistry #ChemistryTutorial #JAMBPastQuestions #WAECPastQuestions #NECOChemistry #O3Schools #StudySmart #ChemistryLessons