Chapter 12
Practice Problems

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1

In the process of taking a gas trom state a to state c along the curved path shown in the illustration above J of heat leave the system and 40 J of work are done on the system. What is the change in internal energy, to the nearest Joule?

2
When the gas is taken along the path cda, the work done by the gas is W = 38 J. How much heat Q is added to the gas in the process cda?
3
If Pa, = Pd, how much work (to the nearest tenth of a Joule) is done by the gas in the process abc?
4
In problem 3), if U a -U c =20J, what is Q (to the nearest Joule) for path abc?
5
Consider the following two-step process. Heat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from 5 atm to atm. Then the gas expands at constant pressure, from an initial volume of 200 L to a final volume at which the temperature reaches its original value. See the illustration at right. Calculate the total heat flow, to the nearest Joule, into or out of the gas.
6
An ideal gas expands at a constant pressure of atm from 300 L to 900 L. Heat then flows out of the gas, at constant volume, and the pressure and temperature are allowed to drop until the temperature reaches half of its original value. What is the total work (to the nearest Joules) done by the gas in the process?
7
In problem 6) what is the total heat (to the nearest Joules) flow into the gas?
8
One kilogram of water is taken from degrees C to degrees 80 degrees Celsius. Estimate the change in entropy (to the nearest J/K) of the water.
9
What is the change in entropy (to the nearest J/K) of grams of water at 0 degrees C when it is frozen into ice at 0 degrees C?
10
If the water in problem 9) were frozen by being placed in contact with a temperature reservoir at -30 degrees C, what would be the total entropy change (to the nearest J/K) of the reservoir and water taken together?



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