Question

You bake chocolate chip cookies and put them, still warm, in a container with a loose (not airtight) lid. What kind of process does the air inside the container undergo as the cookies gradually cool to room temperature (isothermal, isochoric, adiabatic, isobaric, or some combination)? Explain.

Short answer

The process is isobaric due to constant atmospheric pressure.

Step-by-step solution

Significance of pressure

It is described as the force applied/ exerted at 90 degrees to the plane surface of any object over an unit area. It is measured in Pascal or$\mathbf{N}\mathbf{/}{\mathbf{m}}^{\mathbf{2}}$.

Analysis of the processes involved inside the container

Heat flows out then the air cools that’s why the process is not adiabatic, the temperature decreases so it is also not isothermal and the volume of air that was originally in the container decreases, so not isochoric.

Since the container is open to the air in the room, the pressure which is inside the given container is constant (unchanged), which is always equal to the air pressure in the room. Therefore, the process is considered as an isobaric.

Hence, the process is isobaric due to constant atmospheric pressure.