-
Constant-Pressure process (or ______ process) (______' law):
Pi = ___
What does this mean for final and initial volume/temperature
- Isobaric process
- Charles' law
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With a fixed piston, the system is in _______, pressure must be the same on both sides of the piston
With a movable piston, because the external pressure doesn't change, the gas pressure remains ________ as the gas expands
An isobaric process appears on a pV diagram as a ________ line
- equilibrium
- constant
- horizontal line
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An isobaric process is one that occurs at a _______ _______. The values of the heat and the work are generally both _______ values.
W = ____ = _______
p is the ______ ______
From the First Law:
ΔEth = ___ + ___ = ___ - _____
- constant pressure
- nonzero
- W = -Wgas = -p(Vf - Vi)
- constant pressure
- ΔEth = Q + W = Q - p(Vf - Vi)
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Constant-Volume or ________ Process (________'s law):
Vi = ___
pi/Ti = ___
As the temperature increases, the pressure __________
A constant-volume process appears on a pV diagram as a _______ ______
- Isochoric
- Guy-Lussac's law
- Vi = Vf
- pi/Ti = pf/Tf
- increases
- vertical line
-
Isochoric Process
An ________ process is one in which there is no change in the volume
ΔV = ___ ⇒ W = ____
From the First Law:
ΔEth = ____
-
Isochoric process
If energy is added by heat to a system kept at constant volume, all of the transferred energy remains in the system as an increase in its _______ ______
internal energy
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Constant-Temperature Process (or _______ process) are under _______'s law:
Ti = ___
piVi = _____, making it ______
- Isothermal process
- Boyle's law
- Tf
- pfVf, making it constant
-
An isothermal process appears on a pV diagram as a _______
- hyperbola
-
An ________ process is one that occurs at a constant temperature. Since there is no change in temperature, ΔEth = ___
From the First Law:
Q = ___
Any energy that enters the system as heat must leave the system by _____
- isothermal process
- 0
- -W
- work
-
The graph of an isothermal process is known as an _______. Different temperatures correspond to different ________
- isotherm
- isotherms
-
What is the formula for work done on a ideal gas in an isothermal process?
-
Define adiabatic process and state its first law
- Adiabatic process: a process during which no energy enters or leaves the system by heat, Q = 0
- First Law: ΔEth = Q + W = W
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The curve of the adiabatic compression moves from a _______ ________ isotherm to a ______ _______ isotherm
- lower temperature isotherm
- higher temperature isotherm
-
An adiabatic process is one under which no ______ enters or leaves the system, in other words, no _____ is exchanged with the environment.
State two ways this is achieved and give an example
- heat
- heat
- Thermally insulating the walls of the system
- Having the process proceed so quickly that no heat can be exchanged
- Example: rapidly expanding gas which drops its pressure precipitously and simultaneously cools. This is the principle in a snow-making machine
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Free expansion is a unique _______ process. _____ work is done on the gas, W = ___.
Since Q = ____ and W = ____, ΔEth = ____
- adiabatic process
- No work
- W = 0
- Q = 0 and W = 0
- ΔEth = 0
-
In Free expansion, the ______ and ______ energies are the same, and no change in ________ is expected
- initial and final energies
- temperature
-
A ______ process is one that originates and ends at the same state. This process would not be _______ and on a PV diagram, it appears as a _______ ______.
- cyclic process
- isolated
- closed curve
-
In a cyclic process, the energy added by heat to the system must therefore equal the ________ of the work done on the system during the cycle
ΔEint = ____ and Q = ____
The net work done per cycle = ?
- negative
- 0
- -W
- The net work done per cycle equals the area enclosed by the path on a PV diagram
-
Summarize the Q,W and ΔEth different types of processes
ΔEth = Q+W (6)
-
-
B. solve for T, we know p, V and n is constant
-
-
-
- N = 8 * 1026 atoms of air
- Power = 50 W
- Duration = 10 min
- (energy goes to air particles)
- p(power)Δt(time) = energy = ΔEth (so this is neither of the 6 processes)
- ΔEth = 3/2nR(Tf - Ti) *for monatomic gas
- air is mostly Nitrogen which is diatomic so:
- ΔEth = 5/2nR(Tf - Ti)
- pΔt = 5/2nRΔT = 5/2NKBΔT
- ΔT = 1.09 C
-
-
-
Define energy reservoir
Energy reservoir: an object or part of the environment whose temperature does not noticeably change when heat is transferred between the system and itself
-
Differentiate between a hot and cold reservoir
as well as QH and QC (what do the Qs have in common?)
-
Heat is never spontaneously transferred from a _____ object to a ______ object
- colder
- hotter
-
A heat engine is a device that is able to take energy from a _____ reservoir, transform some into useful _____, and deposit the rest as ______ energy in a ______ reservoir.
- hot
- work
- thermal energy
- cold
-
Label the heat engine
Assume there is no net energy transfer into or out of the heat engine. Thus,
Q H = ____ + _____
All quantities are ______
 - QH = QC + Wout
- positive
-
What is the efficiency formula for a heat engine (3)
-
QH is what you had to pay (why?)
No heat engine can operate without exhausting some fraction of the heat into a _____ _______. It is a fundamental law of matter.
What is the formula for maximum efficiency (or ______ efficiency) of any heat engine
What is the units for temperature
- because this is the energy of the fuel burned
- cold reservoir
- Carnot efficiency
-
- emax = 1 - (TC/TH)
- A. emax = 1 - (303.15/573.15) = .47108
- B. emax = 1 - (303.15/523.15) = .4205
- C. emax = 1 - (293.15/473.15) = .3804
- D. emax = 1 - (283.15/373.15) = .2412
- E. emax = 1 - (273.15/363.15) = .2478
- ans = A.
-
- emax = 1 - (TC/TH)
- emax = 1 - (288.15/513.15) = .4385
-
What is the job of a heat pump?
Since it is a process against the natural direction, what happens to the system?
Thus, QH = ?
All quantities are ______
- To transfer heat energy from a cold reservoir to a hot reservoir
- work is done to the system
- QH = QC + Win
- positive
-
Label the heat pump
-
You can use the heat pump for cooling, e.g. a ________. The ________ _____ _________ (____) is a quantity similar to the efficiency of the heat engine.
- refrigerator
- Coefficient of Performance (COP)
-
State the formula for COP (3) and Maximum COP of a heat pump used for cooling
What units must temperature be in?
-
You can use the heat pump for heating, state an example
State the formula for both COP (3) and the formula for Maximum COP of a heat pump used for HEATING
State the units for temperature
- warming a winter cabin
-
Larger COP means a more _______ heat pump! Unlike the efficiency of heat engine (e<1), COP of heat pump can be _______ than 1
-
- COP = Qc/Win
- COPmax = TC/(TH-TC)
- B. 1 & 4
-
Label the heat engine (11-story)
**The available arrows are just hints and not all of the actual arrows
-
State 4 important characteristics of this heat engine
(previous card)
-
-
Define entropy
Natural processes tend to move toward a state of _______ ________. Only _______ energy has entropy
- Entropy: a measure of the order or disorder of a system
- greater disorder
- thermal energy
-
The ordered, organized motion of the baseball (macroscopic _______ energy) has _____ entropy, while the disorganized random motion of the gas atoms (_______ energy) in a balloon has _____ entropy.
State-wise: Entropy of _____ < Entropy of ______ < Entropy of ______
- kinetic
- low
- thermal
- high
- Entropy of solid < Entropy of liquid < Entropy of gases
-
For a baseball and a balloon, state the the direction and speed of motion of the molecules, the type of motion, and the type of energy
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