Chemistry 111
Page 1 out of 6
Exam III /Fall 2004
Answer Key
Bonus
(02 pts):
Suggest a name for the shark in question
9
of this exam…
Any name will do…
Instructions
.
Failure to show work will result in zero points being awarded in any question,
unless it actually requires no work.
If a blank is provided for an answer, you must enter your
answer in that blank.
1. The root mean square velocity of CO
2
gas (MW = 44.01) is approximately 15.1 m/s at
127°C.
True or
false
?
Show your work!
(03 pts)
The way to prove it is to calculate the actual root mean square velocity to see if it
matches to the one given.
v
rms
=
MW
3 R T
v
rms
=
0.04401kg/mol
3 # 8.314 J/Kmol # 400 K
=
476 m/s.
2. If a reaction follows first order kinetics, then a plot of
ln [A]
versus time should be linear
and the slope would be equal to:
- k
.
(04 pts)
3.
Assuming that time is measured in hours, what would be the units of the rate constant for a
first order reaction?
hrs
-1
.
(02 pts)
The units of first order rate constants are simply inverse time.
4. Assume that we have two containers.
One of these (20.0 L) is filled with nitrogen gas at a
pressure of 1.231 atm at 300 K.
The second container (10.0 L) is filled with nitrogen gas at a
pressure of 2.053 atm at 250 K.
The container that is closest to containing one mole of
nitrogen gas would be…
(03 pts)
a) The first container.
b) The second container.
c)
They both contain one mole of nitrogen gas.
If you actually bother to calculate the moles using the ideal gas law, you will find that
they are both equal to one mole.
However, the question here is looking for which gas is
closest to actually obey the ideal gas law.
That is, which is the gas closest to being ideal.

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