# CHAPTER 2 THERMODYNAMICS: THE FIRST LAW CHAPTER

CHAPTER 2
THERMODYNAMICS: THE FIRST LAW
CHAPTER OUTLINE
HW:
Sect.
See Handout for Text Problems
#15, 18, 22, 24*, 33 + Suppl. Problems (Attached)
*Heat applied at constant pressure.
Material
COVER
1.
Systems and Surroundings ......................................................................... YES
2.
Work and Heat ............................................................................................ YES
3.
The Measurement of Work ......................................................................... YES
NOTE: The text (and HW) uses the expression, “work done by
the system” quite often. This is wby = -won = -w. We will stress
“w”, which is the work done ON the system.
4.
The Measurement of Heat .......................................................................... YES
5.
Heat Influx During Expansion ..................................................................... YES
We will actually cover this material (+ other types of expansion)
towards the end of the chapter, after introducing internal energy
and enthalpy.
6.
The Internal Energy .................................................................................... YES
7.
The Internal Energy as a State Function .................................................... YES
8.
The Enthalpy............................................................................................... YES
9.
The Temperature Variation of Enthalpy ...................................................... YES
Box 2.1 Differential Scanning Calorimetry ............................................................... YES
(Pg. 57) This is a very useful method to study phase transitions,
including order-disorder transitions in biomolecules.
Supplementary Home Work Problems
Chapter 2
S2.1 The constant pressure molar heat capacity of water vapor is 33.6 J/mol-K.
Calculate the final temperature if 2.80 kJ of heat is added at constant pressure to
45 grams of water vapor initially at 150 oC and 1.0 bar.
S2.2 Predict whether q, w, ΔU and ΔH are positive, zero or negative for:
(a) condensation of water vapor to liquid water at 100 oC.
(b) melting of solid benzene at its freezing point, 8 oC.
(c) reversible isothermal compression of a perfect gas.
(d) reversible adiabatic expansion of a perfect gas.
S2.3 Calculate q, w, ΔU and ΔH when 50 grams of O2(g) is compressed isothermally
and reversibly from 1 bar to 20 bar at 50 oC.
S2.4 Calculate q, w, ΔU and ΔH when 50 grams of O2(g) is compressed irreversibly
from 1 bar to 20 bar at 50 oC by applying an external pressure of 20 bar.
S2.5 Calculate q, w, ΔU and ΔH when 50 grams of O2(g) is heated at a constant
pressure of 1 bar from 50 oC to 200 oC. Note: The constant volume heat
capacity of O2 is 21.1 J/mol-K.
S2.6 Calculate q, w, ΔU and ΔH when 50 grams of O2(g) is heated at a constant
volume of 45 L from 50 oC to 200 oC.
S2.7 Calculate q, w, ΔU and ΔH when 50 grams of O2(g) initially at a pressure of 1 bar
and volume of 42 L is compressed reversibly and adiabatically to a pressure of
5 bar and volume of 16 L.