Which one of the following has a positive value?
Correct answer: B. Work done on the system
- A. Heat lost by the system
- B. Work done on the system
- C. Work done by the system
- D. Positive ∆E when heat is lost by the system
Explanation
OPTION A: Heat lost by the system is considered to have a negative value in thermodynamics. It represents the transfer of thermal energy from the system to the surroundings, decreasing the internal energy of the system.OPTION B: If work is done on the system, the system gains energy and the sign of w is positive.OPTION C: Any work done by the system uses energy and the system loses energy, so the sign of w is negative.OPTION D: ∆E is considered to have a negative value when heat is lost by the system. It represents the decrease in internal energy of the system as heat is transferred to the surroundings.
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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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