To calculate the work done when an ideal gas expands against a constant external pressure, we can use the formula for work done in an isobaric process:

W=−PextΔVW = - P_{\text{ext}} \Delta V

Where:

• W is the work done by the gas.

• Pext is the external pressure (in this case, 1 bar).

• ΔV\Delta V is the change in volume (final volume - initial volume).

Step 1: Convert units

• The external pressure Pext is given as 1 bar, but we need it in pascals (Pa) for standard SI units.

  1 bar=105Pa

• The volume change ΔV\Delta V is given in liters. We need to convert it to cubic meters (m³): 1 L=10−3m3

Step 2: Calculate the work

• Initial volume Vi=1L=1×10−3m3

• Final volume Vf=10L=10×10−3m3

• The change in volume ΔV=Vf−Vi=10×10−3−1×10−3=9×10−3m3
• Now, plug the values into the work formula:
• W= −(1×105Pa) ×(9×10−3m3)
• W=−900Pa⋅m3
• Since 1 Pa⋅m3=1J, the work is:
• W=−900J=−0.9kJ
• Final Answer:

  The work done by the gas is −0.9kJ.