posted by Christina on .
Oxygen (O2) has a molar mass of 32.0 g/mol [.032kg/mol].
What is the root-mean-square speed of an oxygen molecule at a temperature of 310 K?
What is its average translational kinetic energy at that speed?
Kav= ?? J
I am having problems with the second half, finding the Kav...
You can get Kav by calculating
(1/2) M [Vrms]^2.
You can also get it from the general rule
Etr,average = (3/2) kT
where k is Boltzmann's constant, 1.38*10^-23 Joule/K. It applies to all molecules.
Here is what I've done, hopefully you can identify where I've gone wrong..
Since when is the mass of an O2 molecule .032 kg?
You missed it by a very large factor. .032kg is aobut one ounce, which would be a very large molecule...
ok, that makes much more sense...
then i'm assuming that:n=2 for O2 and the m is .032 ????
The question is for ONE oxygen molecule. 0.032 kg is the mass of a MOLE of oxygen molecules.
I am beyond lost..I've never had any chemistry and our professor assumed that we had at least a basic knowledge...is there any way you could walk me thought this?
No, for I've forgotton what little physics I knew at one time; however, you know (from your chemistry if not physics) that 1 mol of oxygen (0.032 kg) contains 6.02 x 10^23 molecules. So how much does 1 molecule weigh? The problem is asking for 1 molecule, not 6.02 x 10^23 molecules.