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Thermodynamics PV Diagram

  • Thread starter zaf
  • Start date

zaf

Hello forum members

I have a HW problem on ploting a P-V digram, I worked out a solution..can someone have a look at it and let me know if I am correct

the Question is as follows

2 moles of a monatomic ideal gas initially occupies a volum of 100 liters at a pressure of 100 KPa. The gas then expands iobarically to 200 liters (leg 1->2), followed by an isometric pressure increase to 300 KPa (leg 2-3), and ending in an isobaric expansion to 300 liters (leg 3->4).

Find change in U (internal energy) for each leg
Find W (work) for each leg
Find Q (heat exchange) for each leg


here is part of the solution

T1 = (100000 * .10) / (8.314 * 2) = 601 K
U1 = (3/2)*2*8.31*601 = 14982 J

T2 = (100000 * .20) / (8.31 * 2) = 1203 K
U2 = (3/2)*2*8.31*1203 = 29990 joules

Therefore
U for leg 1->2 is +15008.79 joules

W for leg 1-2 would be 10000 joules, which is P times change in volume

Am i correct so far...if that is so...then i can solve the rest


Zaf
 
39
0
hmmm

Its a while since i did this, but i think thats correct. I got dU by using dU = nCdT = 2 * 12.47 * 602 = 15014 J which is close enough.

Your method for working out the work is correct i think, i also got 10,000 J

What is isometric? i know of isobaric (const pressure), isochoric (const volume), isothermic (const temp), but isometric ive not heard of..

I presume isometric means isochoric?
 

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