If a cylinder equipped with a piston expands against an external pressure of 1.25 atm, increasing the volume of a cylinder by 0.500 L and releasing 25.0 J of heat, what is ΔE for the process?

• A. −88.3 J
• B. −63.3 J
• C. 63.3 J
• D. 0.625 J
• E. −25.6 J

Answer: (A)

Verified step by step guidance

1. Understand the problem: We need to find the change in internal energy (ΔE) for a process where a cylinder expands against an external pressure, increases in volume, and releases heat.
2. Recall the formula for change in internal energy: ΔE = q + w, where q is the heat exchanged and w is the work done.
3. Identify the values given: q = -25.0 J (since heat is released, it's negative), external pressure = 1.25 atm, and change in volume (ΔV) = 0.500 L.
4. Convert the pressure-volume work from atm-L to Joules using the conversion factor: 1 L atm = 101.3 J. The work done by the system is w = -PΔV, where P is the external pressure.
5. Calculate the work done: w = -(1.25 atm) * (0.500 L) * (101.3 J/L atm). Substitute this value into the formula for ΔE: ΔE = q + w.