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a.) An ideal gas expands from a volume of 0.006 m^3 to 0.016 m^3 at a constant p

ID: 717929 • Letter: A

Question

a.) An ideal gas expands from a volume of 0.006 m^3 to 0.016 m^3 at a constant pressure of 2.026 x10^5 Nm^-2. Find the heat required if the change in internal energy is 418 J.

b.) A sample of gas absorbs 4000 kJ of heat:

If the volume remains constant, what is the change in its internal energy?

If the surroundings does 2000 kJ of work on the sample. What is the change in its internal energy?

If the sample expands at atmospheric pressure and does 600 kJ of work on its surroundings. What is the change in its internal energy?

Explanation / Answer

Ans a

Initial volume V1 = 0.006 m3

Final volume V2 = 0.016 m3

pressure P = 2.026 x 10^5 N/m2

Work done by the gas

W = - P(V2 - V1)

= - 2.026 x 10^5 N/m2 x (0.016 - 0.006) m3

= - 2026 J

change in internal energy U = 418 J

From the first law of thermodynamics

U = Q + W

Q = U - W = 418 - (-2026)

= 2444 J

Q > 0 heat added to the system