Choose the correct statement.
Correct answer: A. The first law of thermodynamics is not sufficient to predict the direction of a process
- A. The first law of thermodynamics is not sufficient to predict the direction of a process
- B. In the case of an exothermic reaction, the overall enthalpy of the products is greater than that of the reactants
- C. For the reaction H₂(g) + Br₂(l) → 2HBr(g), the enthalpy change can be calculated from bond enthalpy data alone
- D. At 298K and 1 atm pressure, diamond's standard enthalpy of formation is zero
Explanation
The first law deals with the conservation of energy but provides no information about the direction in which a process will spontaneously occur. The second law, involving entropy, is required to predict the direction of spontaneous change.
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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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