A system absorbs 100 kJ heat and performs 50 kJ work on the surroundings. The change in internal energy of the system is:
Correct answer: A. 50 kJ
- A. 50 kJ
- B. 100 kJ
- C. 150 kJ
- D. 5000 kJ
Explanation
It's calculated by subtracting the work done on the surroundings from the heat absorbed by the system. ΔE=q-W=100-50 (Work done on the surrounding by system is negative). =50 kJ
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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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