Is Temperature Constant in a Pressure-Volume Graph?

[intenzxboi]

Just wondering on a pressure volume graph is the temperature constant??

so does that mean the the heat taken in during the process is the negative of the change in energy of the gas??

 

[cepheid]

Not necessarily. Look at the ideal gas law:

PV = nRT

==> P = nRT / V​

This means that IF T is constant, then the PV curve is given by something that looks kind of like y = C/x. You can see that constant temperatures will therefore define a whole family of curves that look like this (they only differ in what C is). These curves are called isotherms, and the corresponding processes are isothermal. However, almost any other kind of PV curve could be allowed (representing a process in which the temperature DOES change). For instance, there are adiabatic processes (which have no net heat flow), isobaric processes (which occur at a constant pressure and therefore correspond to horizontal lines), isochoric processes (which occur at a constant volume and are therefore vertical lines), and any other curve (which doesn't necessarily fall into any of these categories).