# Based on the postulates of the kinetic molecular theory, what conditions of pressure and temperature would cause a real gas to best simulate an ideal gas?

May 24, 2014

High temperatures and low pressures would cause a real gas to behave like an ideal gas.

#### Explanation:

High Temperatures and Low Pressures would cause a real gas to behave like an ideal gas.

The KMT's postulates that we are most concerned about are:

• No Intermolecular Attractions
• The Volume of the atom is negligible compared to the volume the gas occupies

Let's look at the Intermolecular Attractions section first. (I'm going to bring in a bit of Physics here). These attractions are electrostatic (opposite charges attracting each other) and depend on the charge difference in the atoms and the distance between the atoms. As the distance increases, the attractive force decreases.

Knowing that our goal is to get the atoms as far apart from each other as possible. Looking at the Ideal Gas Law we see that:

$P V = n R T$

Solving for V we get:

$V = \frac{n R T}{P}$

So to maximize V, we need to increase the Temperature (particles move faster and spread out), and decrease the Pressure. We could also reduce the number of gas molecules we have, but that's not always doable.

These changes also address the 2nd postulate by making the volume the gas occupies much larger than the volume of any single atom.

Very similar to the one given in socraticcom here: http://antoine.frostburg.edu/chem/senese/101/gases/faq/real-vs-ideal-conditions.shtml