A gas expands when 606 j of energy is added to it as heat. the expanding gas does 418 j of work on its surroundings.

a. what is the overall change in the internal energy of the gas?

b. if the work done by the gas were equal to 1212 j (rather than 418 j)

A) Heat added Q=606 J

Work W = 418 J

From first law of thermodynamics,

Change in internal energy [ Uf - Ui ] = Q - W

Change in internal energy [ Uf - Ui ]=606 - 418=188 J

Change in internal energy [ Uf - Ui ] = 188 J

b) work W2 = 1212 J

heat exchanged Q2 = ?

Initial energy of this process Ui2=Uf of previous=Ui + 188

Final energy Uf2=initial energy of previous process=Ui

Change in internal energy of second process = [ Uf2 - Ui2 ]

Change in internal energy of second process=Ui - (Ui+188)

Change in internal energy of second process = - 188 J

Q2=W2 + (Uf2 - Uf1)

Q2 = 1212 - 188=1024 J

A)

Q=606 J

W = 418 J

From first law of thermodynamics,

[ Uf - Ui ] = Q - W

[ Uf - Ui ]=606 - 418=188 J

[ Uf - Ui ] = 188 J

b)

W2 = 1212 J

Q2 = ?

Ui2=Uf = Ui + 188

Uf2=Ui

[ Uf2 - Ui2 ] = Ui - (Ui+188)

-188 J

Q2=W2 + (Uf2 - Uf1)

Q2 = 1212 - 188=1024 J

Q added in second step (b) so that internal energy is equal to initial internal energy of step (a) = 1024 J