Which of the following compounds will behave LEAST like an ideal gas at low temperature?

Question

a) He

b) SO2

c) H2

d) N2

e) F2

Answer 1

We can go through the list:

A) He is an inert gas, therefore it will act ideally.

B) SO2 is a larger molecule with specific geometry, therefore it is not likely to behave ideally.

C) H2 is the smallest molecule and due to this it will certainly act idealy.

D) N2 is very inert due to it's strong bond between the nitrogens, therefore it will act ideally.

E) F2 is also quite small, so I would expect it to behave semi-ideally.

From these statements, SO2 is the least likely to behave as an ideal gas,

Answer 2

The ideal gas law is based on particles (atoms or molecules) bouncing around, hitting the walls and each other.  Each collision results in elastic recovery.  Other forces between the particles, such as hydrogen bonding is ignored.  The ideal gas law is nothing more than the first law of thermo applied to billiard balls.

So......which molecule does not fit this scheme?  It's most likely SO2, given its size.  For any temperature, SO2 is moving the slowest due to its mass. Low speed means its more likely to be influenced by other forces.   It's also comprised of three atoms which adds complications.

Answer 3

I would think SO2 since it's the only polar molecule in the group. At low temperatures, the attractive force between molecules is NOT negligible as stated in the ideal gas law because their kinetic energy is low and they aren't moving very fast.