What Affects the RMS Speed Difference Between Helium Atoms and Molecules?

[barrylwires]

Homework Statement

Heat is added until the rms speed of a helium atom has increased 50%. Find new pressure. (Not all parameters given.)

Homework Equations

rms = (3kT/m)^1/2
mass of molecule = mass of mole/N_A
Then, mass of helium molecule is 6.6x10^-26kg

The Attempt at a Solution

Question: Is rms speed of a helium molecule the same as the rms speed of an atom. Yes, because the atoms make up the molecule? No, helium is diatomic (right?) and so that has to be taken into account??

 

[LowlyPion]

Consider that Helium is a monatomic gas.

http://en.wikipedia.org/wiki/Helium