A gas absorbs 200 J of heat and expands against the external pressure of 1.5 atm from a volume of 0.5 Lt  to 1.0 Lt, Calculate the change in internal energy.

a) 120.025 J             b) 115.05 J          c) 135.025 J           d) 124.025 J

Dear Student,

The internal energy can be calculated using equation:

E = q +W 

E = q + PΔV

Given q = 200J

P = 1.5 atm

V2 = 1 L

V1= 0.5 L

W= - P(V2-V1) since work is done by the system the sign will be -ve

W = -1.5(1- 0.5) = -0.75 L atm

W = -0.75 X 101.35 J = -75.98 J

(1L atm = 101.35 J)

E = 200 J - 75.98 J = 124.025 J

So, correct option d) 124.025 J

Regards