Page 16 - Physical Chemistry

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• A substantial number of worked-out examples are included. Most examples are Preface
followed by an exercise with the answer given, to allow students to test their
understanding.

EXAMPLE 2.6 Calculation of H
C P,m of a certain substance in the temperature range 250 to 500 K at 1 bar pres-
sure is given by C P,m b kT, where b and k are certain known constants. If n
moles of this substance is heated from T 1 to T 2 at 1 bar (where T 1 and T 2 are in
the range 250 to 500 K), find the expression for H.
Since P is constant for the heating, we use (2.79) to get
2 T 2 1 T 2
¢H q P nC P,m dT n 1b kT2 dT n1bT 2 kT 2`
2
1 T 1 T 1
1
2
2
¢H n3b1T 2 T 1 2 2 k1T 2 T 1 24
Exercise
1/2
Find the H expression when n moles of a substance with C P,m r sT ,
where r and s are constants, is heated at constant pressure from T 1 to T 2 .
2
3/2
3/2
[Answer: nr(T 2 T 1 ) ns(T 2 T 1 ).]
3
• A wide variety of problems are included. As well as being able to do calculational
problems, it is important for students to have a good conceptual understanding of
the material. To this end, a substantial number of qualitative questions are in-
cluded, such as True/False questions and questions asking students to decide
whether quantities are positive, negative, or zero. Many of these questions result
from misconceptions that I have found that students have. A solutions manual is
available to students.
• Although physical chemistry students
have studied calculus, many of them Integral Calculus
have not had much experience with sci- Frequently one wants to find a function y(x) whose derivative is known to be a certain
ence courses that use calculus, and so function f(x); dy/dx f(x). The most general function y that satisfies this equation is
called the indefinite integral (or antiderivative) of f(x) and is denoted by f(x) dx.
have forgotten much of what they
learned. This book reviews relevant If dy>dx f 1x2 then y f 1x2 dx (1.52)*
portions of calculus (Secs. 1.6, 1.8, and
8.9). Likewise, reviews of important The function f (x) being integrated in (1.52) is called the integrand.
topics in physics are included (classical
mechanics in Sec. 2.1, electrostatics in
Sec. 13.1, electric dipoles in Sec. 13.14, and magnetic fields in Sec. 20.12.)
• Section 1.9 discusses effective study methods.

1.9 STUDY SUGGESTIONS
A common reaction to a physical chemistry course is for a student to think, “This
looks like a tough course, so I’d better memorize all the equations, or I won’t do well.”
Such a reaction is understandable, especially since many of us have had teachers who
emphasized rote memory, rather than understanding, as the method of instruction.
Actually, comparatively few equations need to be remembered (they have been
marked with an asterisk), and most of these are simple enough to require little effort
at conscious memorization. Being able to reproduce an equation is no guarantee of
being able to apply that equation to solving problems. To use an equation properly, one
must understand it. Understanding involves not only knowing what the symbols stand
for but also knowing when the equation applies and when it does not apply. Everyone
knows the ideal-gas equation PV nRT, but it’s amazing how often students will use