1. The First Law of Thermodynamics
q > 0 for heat flow ______ the system
w > 0 for work done ______ the system
For ________ changes of state:
For ________ changes:
U is the ________ energy of the system.
When a system changes from one state to another along an ________ path, the amount of work done is the same, whatever the means employed:
i.e. for
but for
The energy of an ________ system is constant.
For
 No perpetual motion machines!
In any cyclic transformation the work done by a system on its surroundings is equal to the ________ withdrawn from the surroundings.
The energy of the universe is ________ .
Modified by Jed Macosko
11/26/2018

2. Modified by Jed Macosko
Temperature
Two systems in thermal equilibrium are at the same ________ .
If system A is in thermal equilibrium with system B, and A is in thermal equilibrium with C, then B must be in thermal equilibrium with C.
This is a statement of the ________ law of thermodynamics.
_______ temperature:
when
Unit of temperature:
The freezing point in the presence of air, and at 1 atm is 0.01 °C lower than the triple point, because of air solution and increased pressure.
The freezing point of water at 1 atm is K. The boiling point of water at 1 atm is K.
Why not ?
The Celsius scale is defined as
It is possible to define an ________ temperature scale (Kelvin scale) by considering (next slides) the work done in an isothermal ________ expansion/compression…
This absolute T is the scaling factor that relates volume change to work.
Modified by Jed Macosko
11/26/2018

3. Modified by Jed Macosko
Pressure–Volume Work 1
T1,P1,V1 m
T2,P2,V2 h
A = area of piston
Expansion P1 P2 V1 V2 1 2
equation of state (need not be _______)
Expansion into a _______ P2 P1 V2 V1 1 2
Compression
Modified by Jed Macosko
11/26/2018

4. Modified by Jed Macosko
Pressure–Volume Work 2
Multi-stage Expansion P 1 5 3 2 4
_______Expansion
Make steps so small that P 1 2
For _______gases
and at fixed temperature
Modified by Jed Macosko
11/26/2018

5. Modified by Jed Macosko
Pressure–Volume Work 3 P 1 3 4
______________
______________ 2
Consider the cyclic path 1  2  3  4  1
Consider the cyclic reversible path 1  3  1
Even for a cyclic process w depends on _______
Modified by Jed Macosko
11/26/2018

6. Modified by Jed Macosko
Energy vs. Enthalpy
For a change in state at constant volume, no expansion work is done, so
However, for a change in state at constant pressure,
P constant
_______
H, being a function of _______ variables only, is also a _______ variable.
For a general change of state (P and V may both change),
Modified by Jed Macosko
11/26/2018

7. Modified by Jed Macosko
Heat _______
Transfer of heat to a system may result in a rise in T.
path function, so C depends on conditions.
Define:
at constant volume, no work
at constant pressure, only ______ work
From 1st Law,
assume no ____ _______
Similarly
For _______
Modified by Jed Macosko
11/26/2018

8. The Relation Between CP and CV
But since
work needed to overcome
_____________ forces
expansion
per degree
“_______ pressure”
For ideal gases
For liquids and solids
is so small that
Modified by Jed Macosko
11/26/2018

9. Modified by Jed Macosko
Adiabatic Expansion 1
_______ = insulated:
For adiabatic expansion
Free expansion:
Fixed pressure:
_______ expansion:
Substitute appropriate equation of state.
Not useful if ____ changes.
Modified by Jed Macosko
11/26/2018

10. Modified by Jed Macosko
Adiabatic Expansion 2
Reversible adiabatic expansion of _______ ______:
ideal gases only P V2 V1
Also, since
Modified by Jed Macosko
11/26/2018

11. Types of Expansion Work ― Summary
For _______ _______ of expansion
For _______ changes
in general
In an _______ expansion
For _______ expansions T is held constant by leakage of heat into the system from the surroundings.
For an ideal gas
so the internal energy must provide for the work:
In an _______ expansion
For _______ expansion of _______ _______ through a given volume change from the same initial state,
since U is continuously replenished by heat intake to keep the temperature constant.
Modified by Jed Macosko
11/26/2018