identifying when to use w

[Cristian Cortes 1L]

Since there are two equation for w, how will we know which one will use ? (w=-nRTln V1/V2) (w=(-PdeltaV)

[Hasmik Dis 2F]

So the first equation is used for calculating work when pressure is not constant[b], while the other equation is used to calculate work when pressure is [b]constant

[Sam Wentzel 1F 14B]

Decide based on whether or not pressure is constant. (delta p = 0 or not)

[edward_brodell_2I]

I think it is also important to consider if a system can do work on the surroundings based on constant pressure conditions (like the atmosphere) or if it is occurring in an environment of variable pressure. For example, if a fire is burning, then since the surrounding pressure (the pressure of the atmosphere) is essentially constant the reaction will release heat but also do work so it would be w = -PexΔV. But if the system has a pressure that is approximately equal to the external pressure like (Pinternal = 2 atm and Pexternal = 2 atm) then we know that the system will exist in dynamic equilibrium conditions in which both the external and internal pressures are fluctuating slightly and resulting in work done due to one pressure overcoming the other. The system is constantly pushing against a higher external pressure so it would be the integral equation. I like to think of how much pressure the system has to do work against. If a system's pressure is pushing against a much higher or lower pressure, the work done is essentially involving a constant pressure since there is a large pressure difference. But if the system is doing work against an external pressure very close to its internal pressure then it will require more work for the system to do work because the pressures are almost equal and opposite.

[Chinmayi Mutyala 3H]

This depends on whether pressure is constant or not. You can use -P(delta)V when external pressure is constant.

[Olivia Peony Dis 2A]

I think it depends on whether or not your surrounding pressure is constant. The pressure on -P(delta)V refers to external pressure. While the pressure on Pv=nRT refers to the pressure on the gas itself and therefore you can calculate work using the ideal gas concepts.