A system absorbs of heat and performs of work on its surroundings. What is the change in internal energy of the system?
Answer and explanation
Correct answer: C.
- Step 1: State the First Law of Thermodynamics: .
- Step 2: Apply IUPAC sign conventions: heat absorbed by system ; work done BY system on surroundings .
- Step 3: Calculate: .
Answer
.
Why not the others: assigns a positive sign to work done by the system (); inverts both heat and work signs; treats both heat absorption and work done as negative.
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