Chem 254
Assignment 2 Solutions
March 7 2012
Chapter 4
1. Calculate HR for the reaction (1/2) N2(g) + (1/2) O2(g) NO(g) at 500. K.
Assume that the heat capacities of reactants and products remain constant a
Chapter 1 & 2
Intro
Energy is conserved and can be produced by digging out of the ground, through drilling,
etc.
Chemical reaction fusion reaction with the sun
All energy simply flows between its different forms study of that flow is
thermochemistry
Wh
Winter 2013 Chem 254: Introductory Thermodynamics
Chapter 7: Properties of Real Gases . 83
Properties of Real Gases . 83
Compression Factor Z . 86
Law of Corresponding State . 86
Fugacities (pure substances). 87
Chapter 7: Properties of Real Gases
Propert
Midterm exam chemistry 254, Friday March 13, 2009, 2.30-4.30 pm Please answer the following 4 questions and indicate clearly how you obtain your answer. Please read the questions carefully and make sure you answer all parts of the questions. Each question
Winter 2013 Chem 254: Introductory Thermodynamics
Chapter 3: The Math of Thermodynamics . 25
Derivatives of functions of a single variable . 25
Partial Derivatives . 26
Total Differentials . 28
Differential Forms . 31
Integrals . 32
Line Integrals .
Winter 2013 Chem 254: Introductory Thermodynamics
Chapter 5: Entropy . 46
Calculating S for processes in ideal gas . 48
S as a function of changes in P,T,V in pure substances (not mixtures or reactions) . 51
The Second law of thermodynamics. 54
Absolute E
Chemistry 254 Formula Sheet
Equations of State
Ideal Gas
P=
nRT
V
van der
Redlich-Kwong
nRT
n2A
1
P=
V nB
T V(V + nB)
2
nRT
n a
2
V nb
V
P=
First Law of Thermodynamics - Internal Energy and Enthalpy
U = q + w
H = U(T) + (PV) = U(T) + (nRT) = H(T)
q=
Tf
C
Some Important Identities
x n+1
n
x dx =
+ C (n 1)
n+1
1
dx = ln x + C
x
e ax
ax
e dx =
+C
a
cos ax
sin ax dx =
+C
a
sin ax
cos ax dx =
+C
a
z
1
( ) =
x y
(x/z) y
da
d(x n )
d(au)
du
=0
= n x n1
=a
dx
dx
dx
dx
d ln ax
1
de ax
ax
=
=ae
dx
x
dx
d sin
Chapter 8
Phase Diagrams and the
Relative Stability of Solids,
Liquids and Gases
Using the total differentials of U, H, A and G,
we obtain the following expressions:
U
U
(
) = T and (
) = P
S V
V S
H
H
(
) = T and (
) =V
S P
P S
A
A
(
) = S and (
) = P
T
Chapter 6
Chemical Equilibrium
We left Chapter 5 considering Stotal > 0 as the
criteria for determining the direction of
spontaneous change. Determining Ssurroundings
can be problematic, as its not always clear
where we can draw the line around sufficien
Thermochemistry
Chemical energy is stored in the bonds of
molecules. Changes in composition, which occur
during chemical reactions, involve changes in the
energy stored in these bonds, resulting in either
release or absorption of energy, usually as heat,
Chapter 10
Electrolyte Solutions
Molecules vs Ions in Solution
The thermodynamics of solvation are much
harder to measure (the problem of zero)
Interactions between charged ions in
solution are much longer in range, and much
more dominant, than interact
Getting Started: Some Terminology
System - defined by
its interactions with
its.
Surroundings everything else in the
universe that isnt the
system
Can be simple.
Or complex!
Whether simple or
complex, the
interface between
the system and
surroundings i
State Functions:
Internal Energy and Enthalpy
Remember that thermodynamics was derived by
observing phenomena and conducting experimental
measurements on bulk systems.
Typically, this means that we observe changes in
one property as a function of changes
Winter 2013 Chem 254: Introduction to Thermodynamics
Chapter 1: Gases . 9
Ideal Gas Law . 9
Van der Waals Equation of state . 10
Partial Pressure (only for ideal gases) . 11
Chapter 1: Gases
Ideal Gas Law
PV nRT
P = pressure in N m -2
V = volume in m3
n =
Ch. 3
State Functions: Internal Energy and Enthalpy
Increase pressure on a substance, volume will shrink
U depends on V and T
Change in q depends on the path we take (thats why we put a slash on d for q because
it is path dependent or an inexact differ
Ch. 4
Thermochemistry
Now we talk about changes in composition which can change the internal energy and
enthalpy of a system
A chemical reaction resulting in a change in enthalpy can occur in conditions such as
constant volume, constant pressure, open s
Ch. 5 Part 1
What Drives a Change in State?
U (internal energy) for an ideal gas is independent of volume (as long as you keep T
constant)
The Laws of Thermodynamics
First law: internal function of internal energy and H
What derives the correction of c
Ch. 5 Part 2
Entropy and the Direction of Spontaneous Change
Entropy direction of spontaneous change
Metal rod two connective systems that are isolated from the surroundings
Heat always flows from T1 to T1
Heat leaves region 1 (-q1) and is absorbed by
Ch. 6
Recall One Important Relation.
Gibbs Free Energy: direction of spontaneous change solely from conditions in our system
Determine whether the state can change or not
Clausius inequality: replace inexact differential with two state functions
Helmh
Chapter 7 The Properties of Real Gases
Real vs Ideal Gases
Repulsive wall depends on the size of molecule
Attractive well go to same limiting behaviour whether it is an ideal or real gas
Ideal gas law assumes that particles are point masses and they do
Chem 254
Assignment 1
Due 830 AM, Jan. 25 2012
Chapter 1
1.
Consider a 20.0-L sample of moist air at 60C and 1 atm in which the partial
pressure of water vapor is 0.120 atm. Assume that dry air has the composition
78.0 mole percent N
Chem 254
Assignment 1
Due 830 AM, Jan. 25 2012
Chapter 1
1.
Consider a 20.0 L sample of moist air at 60.oC and one atm in which the
partial pressure of water vapor is 0.120 atm. Assume that dry air has t