Introduction to the First Law of Thermodynamics - Closed Systems: Summary
Key points from this module:
- The first law is an energy balance. For a closed system ΔU + ΔEK + ΔEP = Q + W.
- No mass flow into or out of a closed system.
- Work is done when a gas expands against an external force in a piston-cylinder.
- Q = 0 for an adiabatic process.
- W = 0 if there are no moving parts or electrical currents at boundary.
- Internal energy does not depend on pressure for an ideal gas.
- For liquids and solids, internal energy does not depend significantly on pressure.
From studying this module, you should now be able to:
- Perform energy balances around a closed system.
- Simplify energy balance for a closed system to remove terms that are not important.
- Determine final states of various processes (e.g., constant pressure, adiabatic, constant volume, and constant temperature).
Prepared by John L. Falconer, Department of Chemical and Biological Engineering, University of Colorado Boulder