6 Basic Thermodynamic Processes Free Online FlashCards

What is a thermodynamic process?

A thermodynamic process is a change from one equilibrium state to another.

What sign convention is used for heat and work?

Heat entering the system is positive, and work done by the system is positive.

Does an adiabatic process necessarily have constant entropy?

Adiabatic means no heat transfer; it does not by itself mean the process is reversible or has constant entropy.

What defines an isobaric process?

In an isobaric process, pressure remains constant: $P=\text{constant}$.

How are boundary work and heat related at constant volume?

At constant volume, boundary work is zero, so the heat transfer equals the internal-energy change: $W=0$ and $Q=\Delta U$.

What pressure–volume relation holds during an ideal-gas isothermal process?

For an ideal gas at constant temperature, $PV=mRT$ implies $PV=\text{constant}$.

What is the first law for a closed system with negligible kinetic- and potential-energy changes?

For a closed system with negligible kinetic- and potential-energy changes, the first law is $\Delta U=Q-W$.

What happens to an expanding gas in an adiabatic process?

In an adiabatic process, $Q=0$, so $\Delta U=-W$; an expanding gas that does work cools.

What pressure–volume relation applies to a reversible adiabatic ideal-gas process?

A reversible $or quasi\-static$ adiabatic ideal-gas process with constant specific heats is isentropic and obeys $PV^{\gamma}=\text{constant}$.

Which process models correspond to $n=1$, $n=0$, and $n=\gamma$ in a polytropic path?

In $PV^n=\text{constant}$, $n=1$ gives an isothermal ideal-gas path, $n=0$ constant pressure, and $n=\gamma$ a reversible adiabatic ideal-gas path with constant specific heats.

What does the area under a quasi-equilibrium path on a pressure–volume diagram represent?

For a quasi-equilibrium process, the area under its path on a pressure–volume diagram gives the work done by the system.

What is the boundary-work equation for a constant-pressure process?

For a constant-pressure process, boundary work is $W=P(V_2-V_1)$.