Question

A sample of gas absorbs 4000 kJ of heat and surrounding does 2000 J of work on sample, what is the value of \(\Delta U\)?

• A. 4000 kJ
• B. 2000 kJ
• C. 4002 kJ
• D. 6000 kJ

Hint:

The first law of thermodynamics relates the change in internal energy to heat absorbed and work done by the system: \(\Delta U = Q - W\).

Answer 1

The Correct Option is C

Step 1: Understanding the first law of thermodynamics.
The change in internal energy (\(\Delta U\)) is given by the equation: \[ \Delta U = Q - W \] Where \( Q \) is the heat absorbed by the system and \( W \) is the work done by the system.
Step 2: Applying the values.
We are given that the heat absorbed is \( Q = 4000 \, \text{kJ} \) and the work done by the surroundings is \( W = 2000 \, \text{J} = 2 \, \text{kJ} \). Hence, the change in internal energy is: \[ \Delta U = 4000 \, \text{kJ} - 2 \, \text{kJ} = 4002 \, \text{kJ} \] Step 3: Conclusion.
The correct answer is (C) 4002 kJ.