1. Apr 27, 2006

### nick727kcin

2. Apr 27, 2006

### Curious3141

The rms speed of the molecules of an ideal gas at a particular constant temperature is inversely proportional to the square root of its molecular mass.

Specifically, $$v^2_{rms} = \frac{3kT}{m}$$ where $v_{rms}$ is the rms speed, k is the Boltzmann constant, T is the absolute temperature and m is the molecular mass.

Can you proceed now ?

3. Apr 27, 2006

### nick727kcin

i dont see how to get the mass though

4. Apr 27, 2006

### Curious3141

Molecular mass = sum of atomic masses of constituent atoms.

So atomic mass of Uranium = ? (you're given this for each of two isotopes)

And atomic mass of Fluorine = ? (you need to look this up in a Periodic Table of the Elements)

Take the sum of atomic mass of Uranium plus six times atomic mass of Fluorine = molecular mass of $$UF_6$$ Do the math separately for both $$^{235}UF_6$$ and $$^{238}UF_6$$ to get the molecular masses for each gaseous isotope.

Last edited: Apr 27, 2006
5. Apr 27, 2006

### nick727kcin

thanks so much :!!)

6. Apr 27, 2006

Sure thing.