Free interactive chemistry · SIM-THERMO-004
First law: heat, work and internal energy
A gas in a piston is compressed or expanded. Track heat q, work w and internal energy ΔU.
Open the interactive simulation →How to use this simulation
- Choose a process: isothermal, adiabatic, isobaric, isochoric, free expansion or irreversible.
- Choose monatomic or diatomic gas and set the final temperature or volume.
- Press “Run process” and watch the piston and the P–V diagram.
- Read q, w and ΔU in the energy bookkeeping panel.
What to notice
- ΔU = q + w, always (first law).
- The work is the area under the path on the P–V diagram.
- Adiabatic: no heat flows, so all the work changes the temperature.
Try this
Compare isothermal and adiabatic expansion to the same volume. Which ends at lower pressure?
Try it for free →