1
Exam 1 (PChem for the Biosciences – CHM3400), Feb. 7, 2011
Name
:_______________________________________
UFID
:_____________________
Instructions
:
Use a pen, NOT a pencil
to answer the questions
.
Fill in your name and UFID above. Give
your answers in the blank spaces
following
each question/subquestion. The total credit for this exam is
100 points
. The credit of each subquestion is indicated in bold (
credit
). Numeric values should be given
with a sufficient number of digits and the units must be indicated. Useful tables, physical constants and
formulae for this test are given with the question or at the end of the exam as an Appendix – make sure
that you check the content of the Appendix before reading the questions. Be concise with your answers,
but remember that you are graded on the information that you put down on paper – if intermediate
steps in a calculation are missing and the result is incorrect, no credit can be given.
Always show the
equations and units that you use.
Good luck!
Short questions
:
1.
Draw a schematic of how the absolute zero temperature was determined experimentally in the
1800’s.
(5 pts)
V
α
T at constant P
Upon extrapolating to zero volume, it is found that there must be a zero volume at T= 0 (Kelvin).
2.
In the equation E
kin
= 3/2 k
B
T, where does the ‘3’ come from, and why?
(3 pts)
The ‘3’ is related to the 3 dimensions x,y and z. Since we assume random motion, the average velocity
v
2
/3 = v
x
2
= v
y
2
= v
z
2
.
3.
Based on the units, explain why PV = work.
(4 pts)
P in Nm
2
and V in m
3
, so Nm
2
⋅
m
3
= Nm (units of work)
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
2
4.
∆
U = w + q = constant, w = constant and q = constant. Fully explain how this statement is (in)correct.
(5 pts)
∆
U is the internal energy, and hence a state function. Hence, the statement that
∆
U = work + heat =
constant is correct. However, work and heat are path functions, and hence they are not necessarily
constant. They depend on the path that is taken.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 SEABRA
 Physical chemistry, Thermodynamics, pH, Energy, Entropy, pts, internal energy change

Click to edit the document details