Sign of ΔH represents:
Correct answer: B. Change in enthalpy.
- A. Enthalpy.
- B. Change in enthalpy.
- C. Quantity of heat absorbed.
- D. Quantity of heat evolved.
Explanation
The sign of ΔH represents the change in enthalpy during a chemical reaction. If ΔH is positive, the reaction is endothermic (absorbs heat), and if it is negative, the reaction is exothermic (releases heat). Option B is correct as it accurately defines ΔH. Option A is incorrect because it refers to enthalpy as a state function, not the change. Options C and D describe aspects of ΔH but do not define it as a change in enthalpy.
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About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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