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What is enthalpy change?rncan you give basic notes on the topic "energy change in chemical reaction" ?
Accepted Answer
Enthalpy change (ΔH) represents the heat absorbed or released during a chemical reaction at constant pressure. It's a thermodynamic concept that helps us understand the energy flow in chemical processes. Here are some basic notes on energy changes in chemical reactions:
Exothermic Reactions: Release heat into the surroundings (ΔH Endothermic Reactions: Absorb heat from the surroundings (ΔH > 0). This makes the surroundings cooler. Examples include melting ice and photosynthesis.
Factors Affecting Enthalpy Change:
Nature of reactants and products: Different substances have different bond energies, impacting the heat change during reaction.
Physical state of reactants and products: Solid, liquid, and gas states have different energy levels.
Temperature and pressure: These conditions influence reaction rates and therefore, heat release or absorption.
Measuring Enthalpy Change:
Calorimetry: Measuring the heat change in a controlled experiment using a calorimeter.
Hess's Law: Calculating enthalpy change indirectly using known enthalpy values for related reactions.
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