Problem 18.22 A balloon contains 0.30 mol of helium. It rises, while maintaining
ID: 1481713 • Letter: P
Question
Problem 18.22
A balloon contains 0.30 mol of helium. It rises, while maintaining a constant 312 K temperature, to an altitude where its volume has expanded five times.
How much work is done by the gas in the balloon during this isothermal expansion? Neglect tension forces in the balloon.
Express your answer using two significant figures.
W = ? kJ
Problem 17.39
A 3700 mL flask is initially open in a room containing air at 1.00 atm and 20 C. The flask is then closed and immersed in boiling water. When the air in the flask has reached thermodynamic equilibrium, the flask is opened and air is allowed to escape. The flask is then closed and cooled back to 20 C.
Part A:
Find the maximum pressure reached in the flask.
Express your answer with the appropriate units.
p_max = ?
Part B:
Find the number of moles that escape when air is released.
Express your answer with the appropriate units.
n = ?
Problem 18.26
Nitrogen gas ( = 1.4) at 13 C is compressed adiabatically until its volume is reduced to one-fourth of its initial value. By how much does its temperature increase?
Change in temperature = ? C
Problem 18.15
In a perfectly insulated container, 2.5 kg of water is stirred vigorously until its temperature rises by 7.0 C.
How much work was done on the water?
Express your answer using two significant figures.
W = ? kJ
Problem 18.46
An ideal gas with =1.4 occupies 3.5 L at 300 K and 140 kPa pressure and is compressed adiabatically until its volume is 2.0 L. It's then cooled at constant pressure until it reaches 300 K, then allowed to expand isothermally back to state A.
Part A
Find the net work done on the gas.
Express your answer using two significant figures.
W = ? J
Part B
Find the minimum volume reached.
Express your answer using two significant figures.
V = ? L
Problem 18.42
A gas expands isothermally from state A to state B, in the process absorbing 35 J of heat. It is then compressed isobarically to state C, where its volume equals that of state A. During the compression, 22 J of work are done on the gas. The gas is then heated at constant volume until it returns to state A. Draw a pV diagram for this process.
Part A
How much work is done by the gas during the complete cycle?
Express your answer using two significant figures.
W = ? J
Part B
How much heat is transferred from the gas as it goes from B to C to A?
Express your answer using two significant figures.
Q_BCA = ? J
Explanation / Answer
18.22)
W =n*R*T*ln (V2/V1)
= 0.3*8.314*312* ln (5)
= 1252.45 J
Answer: 1252.45 J
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