Heat of formation (∆Hf°) for CO2 is:
Correct answer: A. -394 kJ/mol
- A. -394 kJ/mol
- B. +394 kJ/mol
- C. -294 kJ/mol
- D. -390 kJ/mol
Explanation
The heat of formation (∆Hf°) for carbon dioxide (CO2) is: ∆Hf° = -394 kj/molThe negative sign indicates that the formation of one moleucle of CO2 from its constituent elements (carbon and oxygen) releases 394 kj of energy. In other words, it is an exothermic process, where energy is released during the formation of CO2 .
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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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