Question

A gas is compressed from an initial volume of 5.40 L to a final volume of 1.22 L by an external pressure of 1.00 atm. During the compression the gas releases 120 J of heat. What is the change in internal energy of the gas?

Answer 1

W = -Pext(Vf-Vi)

P = 1.0atm

Vi = 5.4 L

Vf = 1.22 L

put values in above expression

W = -Pext(Vf-Vi)

= -1.0atm (1.22L - 5.4L)

= 4.18 atm.L

= 4.18 *101.33 J

= 423.56 J

Q = -120 J (negative because heat is released)

W = 423.56 J

we have below equation to be used:

deltaU = Q + W

deltaU = (-120.0 J) + (423.56 J)

deltaU = 303.56 J

Answer: 304 J

After adjusting the number of significant figures