Chapter 5 – Which Sections for the Exam?
Chapter 5:
All sections except section 5.11 were
covered. Section 11 is an interesting section on
atmospheric chemistry.
Fundamentals
Know how to calculate molar mass. Know your
nomenclature (still). Be able to calculate amounts of
reactants or products when given amounts of reactant or
products – this is called stoichiometry – KNOW IT. See
chapters 13 Know how to determine the limiting
reactant and how much product it leads to. Be able to
incorporate percent yield into a problem if necessary.
All that is new is moles to P or V instead of grams.
How to measure pressure
Know the basics of how a manometer works and how a
barometer works. Know how to calculate the pressure
due to a standing column of liquid:
P = dgh
or
P =
ρ
gh
d
and
ρ
(rho) are density. Watch your units here.
Pressure will be in Pascals if you use kg/m
3
for density,
and m for height. If the column is mercury, just get the
height in mm and you’ve now got torr.
Gas Laws
Know the NAMES and the law associated with each
name (scientist).
Boyle’s Law:
Pressure is inversely proportional to
volume (assuming constant temperature and amount of
gas, moles). Any units will work here.
P
∝
1
V
P
1
V
1
=
P
2
V
2
= constant
Charles’ Law:
Volume is directly proportional to
absolute
temperature (assuming constant pressure and
amount of gas, moles). Any units for volume but
remember,
T
must be Kelvin.
V
∝
T
V
1
T
1
=
V
2
T
2
= constant
Avogadro’s Law:
Volume is directly proportional to
amount of gas in moles. (assuming constant temperature
and pressure).
V
∝
n
V
1
n
1
=
V
2
n
2
= constant
Combined Gas Law:
Most books and people refer to
this as Boyle’s Law + Charles’ Law which is
P
1
V
1
T
1
=
P
2
V
2
T
2
(assuming constant
n
)
However, our book throw’s in Avogadro’s Law also
giving:
P
1
V
1
n
1
T
1
=
P
2
V
2
n
2
T
2
= constant
which is fine, except that this is really just the
Ideal Gas Law
in disguise. The constant that is defined
by this version of the combined gas law is the Universal
Gas constant,
R
. So by definition:
R
=
PV
nT
which rearranges to give
PV
=
nRT
which is the
Ideal Gas Law
we all know and love.
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 Spring '07
 Fakhreddine/Lyon
 pH

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