# Groupwork 1 Properties of Gases

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Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

Useful Equations

$$1joule=1\frac{kgm^2}{s^2}$$        $$1Pa=1\frac{N}{m^2}=1\frac{kg}{ms^2}$$        $$1bar=10^5Pa$$

$$1atm=1.01325bar=1.01325x10^5Pa=760torr$$

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The ideal gas law, $$Pv=nRT$$provides a framework for us to think about gases.

Which parts of the ideal gas law depend on the amount of material present?  Which ones are independent of the amount of material present?

A variable that depends on the amount of material is called extensive while one that does not depend on the amount of material is called intensive.  Which variables in the ideal gas law are extensive and which are intensive?

If we divide an extensive variable by the number of particles in a system, we convert our extensive variable to an intensive quantity.  Usually, we divide by one mole of a substance and designate the new intensive variable by a "bar" above the extensive variable.  Given this definition, what does the notation, $$\bar{V}$$mean to you?

Rewrite the ideal gas law using $$\bar{V}$$.

What are the assumptions of the ideal gas law? Under what conditions do you think that gases will follow the ideal gas law?  Discuss and explain.

On the graph below, plot $$\bar{V}$$ versus T for an ideal gas at 0.20 and 0.40 bar. What is the limit of $$\bar{V}$$as T approaches zero?  FYI:  $$R=8.3145\frac{J}{mol*K}=0.083145\frac{L*bar}{mol*K}$$

We define the compressibility of a gas as $$Z=\frac{P\bar{V}}{RT}$$.  On the graph below, plot Z versus P for an ideal gas at T=300K. Where on your plot would you expect a real gas to behave ideally?

What would your plot look like for a real gas?  Explain any features different from an ideal gas.