Worcester Polytechnic Institute
Chemical Engineering Department
ChE 2013 Applied Chemical Engineering Thermodynamics C Term 2014
Homework 3 — Due Wednesday 2/5
3.1. Generate an x—y diagram and a T-x—y
Thermodynamics
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1
Attractive forces
That attractive forces exist between molecules is clearly
demonstrated by the fact that a gas can be liquefied. The
effect of these
Thermodynamics
CH 3510
Christopher Lambert
If you need course adaptations or accommodations because
of a disability, or if you have medical information to share with
me that may impact your performanc
Thermodynamics
1
Things to know and do
MW of common elements
Common physical constants and conversion
factors
Predict the result of a calculation
Evaluate logarithms and draw graphs
Structure of
Thermodynamics
Reversibility
P
A
P1
P2
PF
V1
B
V2
V
2
Reversibility
If the gas expands reversibly then the amount of work that
can be done is given by
V2
w
PdV
V
1
Which is the area of the figure AB
Thermodynamics
Highest Mountain in South America
1
Refinement
Our derived expressions
then become:
Collision frequency
Collision density (A alone)
Collision density (A and B)
2
2d A u A N A
ZA
V
2
2
Thermodynamics
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1
The Constants
The constants, including R can be expressed in
terms of the measureable parameters, Pc, Vc and
Tc. Pc and Tc are easier to measure than Vc.
Thermodynamics
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1
The Kinetic Theory of Gases
We assume the following:
The gas consists of tiny particles
Particles are points and have no volume
There
Thermodynamics
1
Molecular Speeds
The average kinetic energy per mole of gas is given by:
U 1 2 M u 2 3 2 RT
u2
u2
3RT
3RT
or u 2
M
M
Is the root mean square or RMS velocity.
2
Examples
Compare the
Thermodynamics
1
Equipartition of Energy
Molecules in thermal equilibrium have the same
average energy associated with each independent
degree of freedom of their motion and that the
energy per molecu
Thermodynamics
Things to know and do
MW of common elements
Common physical constants and
conversion factors
Predict the result of a calculation
Evaluate logarithms and draw graphs
Structure of co
Thermodynamics
Cascade du Sallanches
Cascade de lArpenaz
1
Bomb Calorimeter
http:/www.colby.edu/chemistry/PChem/lab/EnthalpyofFormation.pdf
2
Bomb Calorimeter
3
Experiment
The calorimeter is calibrate
Thermodynamics
1
Enthalpy and Internal Energy
For a system at constant pressure that undergoes a
change in volume:
H U PV
For a reaction that involves the generation of a gas, for
example:
H U nRT
At
Thermodynamics
1
Equipartition of Energy
Molecules in thermal equilibrium have the same
average energy associated with each independent
degree of freedom of their motion and that the
energy per molecu
Derivation of Constants in the van der Waals Equation
RTC
PC
V b
C
RTC
2a
0 3
VC VC b 2
a
2
V
C
(i)
0
2 RTC
VC b
(ii)
3
6a
4
VC
(iii)
Solve (iii) for a
a
4
2 RTCVC
6VC b
RTC
VC b
2
3
an
Thermodynamics
1
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2
In General
For the mixture:
Remember this
For 1 mole of mixture:
Forget this
S R ni ln xi
i
S R xi ln xi
i
3
Entropy change as a funct
Thermodynamics
1
Free Energy of Reaction
Lets look at the formation of hydrogen gas:
H+H
H2
The standard enthalpy of formation and the
standard entropy of the reactants and products are:
fH (kJ mol-1)
Problem Set 2
September 4, 2008
Answers are due at the beginning of class Friday September 11, 2005. Answer sets received
after 10:00 am will not be graded.
1. A hiker with backpack weighs a total of
Thermodynamics
1
A general cycle can be
divided into small
Carnot Cycles. The
match is exact in the
limit of infinitesimally
small cycles. Paths
cancel in the interior of
the collection and only
the p
Set Three
1. An electric motor requires 1.5 kilo Watt-hour to run for a specified period of time. In this
same time it produces 1800 kilojoules of mechanical work. How much energy is dissipated in
fri
1. Calculate the density of air at sea level when the temperature is 21C? Assume an average
molecular weight for air of 28.8 g mol-1. Your answer must be given in units of kg m-3.
P
nRT
V
nM
V
n
V
M
P
Thermodynamics
1
Entropy and Ideal gases
Consider an ideal gas that undergoes a change
in volume and temperature. Calculate the
entropy change associated with this change.
dU dq dw dq PdV
dq dU PdV
RT
Thermodynamics
www.youtube.com/watch?v=Ut1kGmOhzWQ
1
The Second Law of Thermodynamics
(Engel and Reid, p79 85; McQ. & S. 20 to 20.3)
Its going to happen, happen, happens all the time. (The undertones)
Review of the First Law of
Thermodynamics
Review of the First Law of the
movement of heat
The Equation of State
Consider the gas laws:
PV nRT
P = Pressure
R = Gas constant
V = Volume
T = Temperature
N
Thermodynamics
Britton Hill
1
Bomb Calorimeter Calculation
If ethanol is combusted in a bomb calorimeter
C2H5OH (l) = 3O2(g)
2CO2(g) + 3H2O(l)
The amount of heat produced in the bomb calorimeter is 13
Thermodynamics
Cascade du Sallanches
1
Standard Enthalpies and Stoichiometry
The enthalpy changes associated with a reaction make use of a quantity called the extent of a reaction. The extent of a rea
Thermodynamics
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1
Adiabatic Expansion
In an adiabatic expansion no h
Thermodynamics
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