- #1
mmwave
- 647
- 2
An unknown number of Helium atoms are in a 1 liter container at an unknown temperature. The gas is made to expand such that it's final volume is 4 liters and pressure rises 'in direct proportion to its volume'.
1. does 'in direct proportion to it volume' mean Pf = Pi * Vf/Vi or should there be a proportionality constant a?
2. I calculated the work done on the gas by using P(v) = a*V and using W = -[inte] aVdV = -a/2 * (Vf^2 - Vi^2) Comments?
3. I am having more trouble getting change in internal energy dU.
I tried PV = NkT so PfVf - PiVi = Nk( Tf - Ti) and
dU = 3Nk (Tf - Ti)/2 so that
dU = 3/2 * (PfVf-PiVi) = 3/2 * (4*4*aVi - Vi)
Is this even close?
4. If I can get 2 and 3 I can calculate Q myself!
1. does 'in direct proportion to it volume' mean Pf = Pi * Vf/Vi or should there be a proportionality constant a?
2. I calculated the work done on the gas by using P(v) = a*V and using W = -[inte] aVdV = -a/2 * (Vf^2 - Vi^2) Comments?
3. I am having more trouble getting change in internal energy dU.
I tried PV = NkT so PfVf - PiVi = Nk( Tf - Ti) and
dU = 3Nk (Tf - Ti)/2 so that
dU = 3/2 * (PfVf-PiVi) = 3/2 * (4*4*aVi - Vi)
Is this even close?
4. If I can get 2 and 3 I can calculate Q myself!