IG Chemistry-7 Chemical energetics (7.2)

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What is the definition of enthalpy (ΔH)?

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Enthalpy (ΔH) is a measure of the total heat content of a system, used to quantify the energy changes during a chemical reaction.

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What does a negative ΔH value indicate in a chemical reaction?

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A negative ΔH value indicates that the reaction is exothermic, meaning it releases energy to the surroundings.

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What is the standard unit of energy in chemistry?

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The standard unit of energy in chemistry is the Joule (J).

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How is the enthalpy change (ΔH) calculated for a reaction?

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ΔH is calculated by subtracting the total enthalpy of the reactants from the total enthalpy of the products.

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What is the significance of the enthalpy of formation?

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The enthalpy of formation is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.

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What is the relationship between bond energy and enthalpy change?

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The enthalpy change of a reaction can be estimated by the difference between the total bond energies of the reactants and products.

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What is an endothermic reaction?

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An endothermic reaction is a chemical reaction that absorbs energy from its surroundings, resulting in a positive ΔH.

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What is the formula for calculating the heat energy (q) absorbed or released?

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q = m × c × ΔT, where m is mass, c is specific heat capacity, and ΔT is the change in temperature.

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What is the principle of conservation of energy in chemical reactions?

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The principle of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another.

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What is the role of catalysts in chemical reactions?

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Catalysts speed up chemical reactions by lowering the activation energy without being consumed in the process.