# Physical Chem, work of a non-ideal gas

#### chelovek

I have a problem where I am given an equation of state pV=RT+(bRT-a)/V and asked to find the work produced in the isothermal, reversible expansion from V1 to V2.

I thought I would want to use W=-integral(nRT/V)dV, but that is apparently only for ideal gases, and this problem concerns a non-ideal gas, according to my professor.

1) How do I know by looking at the problem that this doesn't concern an ideal gas. (the equation given does look like the van der Waals equation...)
2) Since it isn't an ideal gas, what equation can I use? w=-integral(Pext*dV)?
.
Any ideas? I'm feeling really lost here conceptually

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#### gravenewworld

I have a problem where I am given an equation of state pV=RT+(bRT-a)/V and asked to find the work produced in the isothermal, reversible expansion from V1 to V2.

I thought I would want to use W=-integral(nRT/V)dV, but that is apparently only for ideal gases, and this problem concerns a non-ideal gas, according to my professor.

1) How do I know by looking at the problem that this doesn't concern an ideal gas. (the equation given does look like the van der Waals equation...)
2) Since it isn't an ideal gas, what equation can I use? w=-integral(Pext*dV)?
.
Any ideas? I'm feeling really lost here conceptually

1.) The fact that you are using the Van der Waals eq. of a gas means you are dealing with a non ideal gas. PV=nRT is only for an ideal gas.

2.) What is the pressure in terms of volume for the non ideal gas? Once you find pressure in terms of volume you can solve for the work from W=-int P(V)dv