Question

can you check my answer on where did i get wrong? xD

Answer 1

the question i copied is wrong. :)


Two moles of N2 gas undergo the cycle abcd. The pressure of the gas in each state is:
pa = pd = 600 Pa ;
pb = pc = 2000
.The volume of the gas in each state is:
Va = Vb = 2.00m^3 ;
Vc= Vd 9.00m^3 .

The gas may be treated as ideal.
Find the total work done on (or by) the gas in the complete cycle?

My Solution:

from a to b volume is constant so therefore W = 0
from b to c pressure is constant , so W = p(Vc-Vb) = 2000(2-9) = -14000 J
from c to d volume is constant so therefore W = 0
from d to a pressure is constant, so W = p(Va-Vd) = 600(9-2) = 4200J

W(total) = 0 - 14000J + 0 + 4200J = -9800J

Answer 2

change in pressure will take work too, even if the volume is constant. to increase the pressure in a given volume you must add energy.
you need to account for the temperature changes and the energy required to make those changes.
PV=nRT