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.

  1. Step 1: State the First Law of Thermodynamics: .
  2. Step 2: Apply IUPAC sign conventions: heat absorbed by system ; work done BY system on surroundings .
  3. 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.

Practise more Chemical thermodynamics and thermochemistry.

Free questions with an explanation for every one, and full timed JEE Main mock tests.