Question

The volume of gas decreases from 500 cc to 300 cc when a
sample of gas is compressed by an average pressure of 0.6
atm. During this process 10 J of heat is liberated . The change
in internal energy is.
(a) –2.16 J (b) 12.15 J (c) 2.16 J (d) 101.3 J

Answer 1

Therefore the change of internal energy is = 2.16 J

Explanation:

Change of volume = (500-300)cc= 200 cc=  0.2 liter

P = pressure = 0.6 atm

work done =force × displacement

                  = pressure ×(cross section area × displacement)

                  = pressure × change of volume

                  = (0.6×0.2) atm-lit

                   =0.12 atm-lit

1 atm-lit = 101.33 J

∴0.12 atm-lit= (101.33×0.12) J = 12.1596 J

Since during the process 10 J of heat is liberated so,it  will be negative.

Therefore the change of internal energy is = (12.1596-10)J

                                                                    =2.1596 J

                                                                   ≈2.16 J