During adiabatic expansion the exchange in internal energy of 2 moles of a gas is -100J, the work done during the expansion is:
Correct answer: D. 100J
- A. Zero
- B. -100J
- C. 200J
- D. 100J
Explanation
During adiabatic expansion, there is no exchange of heat between the system and its surroundings. This means that the change in internal energy (ΔU) is solely due to the work done on or by the system. The first law of thermodynamics states: ΔU = Q - W Where: ΔU = Change in internal energy Q = Heat added to the system W = Work done by the system In this case, since the expansion is adiabatic (no heat exchange), the equation simplifies to: ΔU = -W -100J = - W (negative signs cancel out) W = 100J
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About First Law of Thermodynamics
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
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