Question

OPEN-ENDED PROBLEMS: to receive credit, you need to show calculations Problem 1 (1 pressure. Neon has a molar specific heat of 20.79 J/mol-K for a constant-pressure process 0 points): Two moles of neon gas is heated from 300 K to 420 K at constant a) (3 points) Calculate the energy Q transferred to the gas; b) (2 points) Calculate the change in the internal energy of the gas; c) (3 points) Calculate the work done on the gas during this process. d) (2 points) Draw a sketch of PV-diagram for this process (showing the shape of the graph is sufficient)

Answer 1

A.

For isobaric process,

energy transferred to the gas is given by:

Q = n*Cp*dT

n = number of moles = 2

Cp = Molar specific heat at constant pressure = 20.79 J/mol-K

dT = 420 - 300 = 120 K

So,

Q = 2*20.79*120 = 4989.6 J

Part B.

Change in internal energy is given by:

dU = n*Cv*dT

Cv = Cp - R = 20.79 - 8.314 = 12.476

So,

dU = 2*12.476*120 = 2994.24 J

Part C.

Using first law of thermodynamics

dQ = dU + W

W = dQ - dU

W = 4989.6 - 2994.24

W = 1995.36 J = Work-done on the gas

Part D.