NEET2017ChemistryThermodynamics (C)Actual
A gas is allowed to expand in a well-insulated container against a constant external pressure of   2 . 5   atm from an initial volume of 2 . 50   L to a final volume of 4 . 50   L . The change in internal energy ΔU of the gas in joules will be
Options
- A1136 . 25   J .
- B- 500   J .
- C- 505   J .
- D+ 505   J .
Correct answer
C. - 505   J .
Step-by-step solution
ΔU = q + w For adiabatic process, q = 0 ∴          ΔU = w = - P ⋅ ΔV =   - 2 .5   atm × 4 .5 - 2 .5 L =   - 2 .5 × 2   L - atm =   - 5 × 101 .3   J = - 506 .5   J ≈ - 505   J