Chemistry · THERMODYNAMICS

During an irreversible expansion of an ideal gas from an initial volume of \( 3.0\text{ L} \) to a final volume of \( 8.0\text{ L} \) against a constant external pressure of \( 2.5\text{ bar} \), the gas absorbs \( 750\text{ J} \) of heat. Given \( 1\text{ L}\cdot\text{bar} = 100\text{ J} \), the change in internal energy (\( \Delta U \)) of the gas is:

1. A
   \( +2000\text{ J} \)
2. B
   \( -500\text{ J} \)
3. C
   \( +500\text{ J} \)
4. D
   \( -1250\text{ J} \)