Chapter 15 Flashcards
In an isothermal process, there is no change in ________
temperature
A gas is expanded to twice its original volume with no change in its temperature. This process is ________
isothermal
An ideal gas is compressed to one-half its original volume during an isothermal process. The final pressure of the gas ________
increases to twice its original value
A gas is quickly compressed in an isolated environment. During the event, the gas exchanged no heat with its surroundings. This process is ________
adiabatic
The process shown on the PV diagram is an ________
isobaric expansion
When water freezes, the entropy of the water ________
decreases
During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal energy of the gas?
zero
During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the work done by the gas in the process?
-5.0 J
An ideal gas undergoes an adiabatic process while doing 25 J of work. What is the change in internal energy?
-25 J
A heat engine receives 7000 J of heat and loses 3000 J in each cycle. What is the efficiency?
57%
A heat engine has an efficiency of 35.0% and receives 150 J of heat per cycle. How much work does it perform in each cycle?
52.5 J
What is the Carnot efficiency of an engine which operates between 450 K and 310 K?
31%
What is the maximum theoretical efficiency possible for an engine operating between 100°C and 400°C?
45%
What is the change in entropy when 50 grams of ice melt at 0°C?
60.9 J/K
What is the change in entropy when 100 g of water at 10°C is mixed with 100 g of water at 40°C?
1.0 J/K
What is the change in entropy when 1 kg of water at 0°C is mixed with 3 kg of water at 20°C?
7.7 J/K
In the closed thermodynamic cycle shown in the PV diagram, the total work done by the gas during a complete cycle is:
postive
clockwise closed cycle = positive total work
counter-clockwise closed cycle = negative total work
A heat engine exhausts 7800 J of heat while performing 2600 J of useful work. What is the efficiency of this engine?
A Carnot engine’s operating temperatures are 210°C and 45°C. The engine’s power output is 950 W. Calculate the rate of heat output.
an irreversible heat engine
*efficiency is smaller than the Carnot engine efficiency so it must be an irreversible heat engine
A restaurant refrigerator has a coefficient of performance of 5.0. If the temperature in the kitchen outside the refrigerator is 32°C, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?
* Coefficient of performance (COP)
Totoal change in entropy for a reversible process is:
zero
If 0.45 kg of water at 100°C is changed by a reversible process to
steam at 100°C, determine the change in entropy of (a) the water, (b) the surroundings, and (c) the universe as a whole. (d) How would your answer differ if the process were irreversible?
