Would someone check my thinking please.
PVT of an ideal gas (nitrogen) are all given.
I've used PV=nRT rearranged to get the number of moles.
Then, U= 3/2nRT to get the internal energy of the sample.
Am I on the right track? Thanks.
well, all you can really define is changes
dU = n Cv dT
but if you say U = 0 at T = 0, I suppose that is ok
for a MONATOMIC ideal gas Cv = (3/2) R
BUT for diatomic (O2, N2 etc) Cv = (5/2)R
So you equation is ok only for changes of temperature (the U depends only on T) for a monatomic ideal g)as
Thanks Damon, I realise I didn't tell you what i'm asked to do!
I note your point about the start point for the equation. Thanks
OK, remember Nitrogen is normally diatomic, N2.
Yes, you are on the right track! Your understanding of the ideal gas law and its rearrangement to calculate the number of moles is correct. The equation PV = nRT relates the pressure (P), volume (V), number of moles (n), gas constant (R), and temperature (T) of an ideal gas.
To find the number of moles (n), you rearrange the equation as follows:
n = PV / RT
Once you have determined the number of moles, you can use the equation U = (3/2)nRT to calculate the internal energy (U) of the gas sample. This equation relates the internal energy to the number of moles (n), gas constant (R), and temperature (T). The factor 3/2 accounts for the degrees of freedom of the gas molecules (assuming they behave as independent particles in a perfect gas).
So, in summary:
1. Use PV = nRT to find the number of moles (n) of the ideal gas.
2. Use U = (3/2)nRT to calculate the internal energy (U) of the gas sample.
Make sure that the values you plug into the equations (pressure, volume, temperature, and gas constant) are in appropriate units and consistent with each other.