H2 + O2 ➞ 2H2O ΔH = +285.5 kJ mol-1What will be the enthalpy change in the above reaction?
Correct answer: A. +285.5 KJ/mol
- A. +285.5 KJ/mol
- B. Zero kJ/mol
- C. -285.5 kJ/mol
- D. 1 kJ/mol
Explanation
ΔH is the heat change in the system. It is calculated by subtracting the sum of energy in reactants from the sum of energy in the products. Heat change of a system is also called the enthalpy change of the system.
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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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