Chemistry 20
Forms of Matter: Gases Notes
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Chapter 3: Properties of Gases
3.1 Gases and the Kinetic Molecular Theory
A. Properties of Gases
 we use many _____________________________ that were designed with
the knowledge of the __________________________________________
eg)
 gases have several distinct _______________________________________
properties:
 gases are _____________________________________
ie) _____ pressure = ______ volume
 gases _______________ as temperature ___________________
ie) _____ temperature = _____ volume (not confined)
_____ temperature = _____ pressure (confined)
 gases have _______________________________________________
…allows them to escape quickly through small openings
 gases have _________________________________
 gases ___________________________________________________,
they all are ________________
 gases have __________________________________________, they
__________________________________ of the container they are in
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B. Kinetic Molecular Theory
 we need ___________________ to describe how gases behave on the
molecular level
 the _____________________________________ says that all particles are
____________________________________________________________
 an ________________________________________________________ is
defined by the following characteristics:
1. the gas molecules are in __________________________________
where they ______________________________________ until they
_______________ with a particle or wall of the container
2. the gas molecules are ___________________________ (they have
_____________ but no ___________________)
3. the only interaction between molecules of the gas and container are
_____________________________________…collisions where
_______________________________ is _________________
 ___________________ do not have these perfect characteristics however
their behaviour is _______________________________________ of ideal
gases
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3.2 Gases and Pressure
A. Atmospheric Pressure
 although gas molecules in the atmosphere have ______________________,
the Earth’s _____________________________________ keeps them near
the surface of the planet
 pressure = ________________________________________
 pressure is exerted ______________________________________________
 atmospheric pressure is the _____________ that a column of air exerts on a
______________________________ on the _________________________
 air is _______________________________ as altitude ________________
______________ pressure is exerted
B. Measuring Pressure
 Pascal and Perier used ____________ to prove that atmospheric pressure
_________________________________________________
 the work of Pascal, Perier and Torricelli all led to the development of the
_________________________________________
 there are several different units used to measure pressure:
 ________________________________________________________
 the ___________________________________________
 the ___________________________________________
 the ___________________________________________
 the ________________
 you will be using the standard unit of _________ in gas law calculations and
therefore you must be able to convert mmHg and atm to kPa
 memorize the following _________________________________________:
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 another conversion: ______________________________________
 to convert other units of pressure to kPa, set up a _______________
Example 1
Convert 650 mmHg to kPa.
Example 2
Convert 2.5 atm to kPa.
Try These:
Convert the following pressures to kPa:
1. 4.0 atm
2. 855 mmHg
3. 0.625 atm
4. 150 mmHg
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C. Boyle’s Law
 Irish scientist _____________________________ studied the relationship
between the ________________ and _________________ of gases at
___________________________________________
 pressure on the walls of a container is caused by the ___________________
_______________________________________________________________________
 as you _____________________________________ of a contained gas,
there is ____________________ for the gas particles so they ____________
______________________
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 _______________________________ = ____________________________
Volume vs. Pressure for a Gas
 Boyle’s Law states that __________________________________________
____________________________________________________________
____________________________________________________________
eg) lungs – to inhale, we ___________________ the volume of our chest
cavity which _______________________ the pressure which
makes the air move in
breath-hold diving – all air containing spaces in body _____________ as
pressure _________________________ with depth…this
doesn’t happen with SCUBA gear
where:
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Example 1
A balloon is filled with 30.0 L of helium gas at 100 kPa. What is the volume
when the balloon rises to an altitude where the pressure is only 25.0 kPa?
(assume constant temperature)
Example 2
The pressure on 2.50 L of anesthetic gas is 100 kPa. If 6.25 L of gas is the
required volume, what pressure must it be under assuming constant
temperature?
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3.3 Gases and Temperature
A. Volume vs. Temperature
 when
_______________________________________ of a gas are graphed, the
plot is _____________ (as long as amount of gas and pressure were
constant)
 it was also noticed that when these linear plots were __________________
down to ____________________________, all the lines _______________
at one point
Volume vs. Temperature for a Gas
 the temperature when the volume of a gas is __________ is ____________
 _____________________, in 1848, suggested that this is the lowest
possible temperature or _____________________________________
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 he established a new temperature scale which is called the _____________
scale in his honour
 _____ is used for temperature in _________
 ______ is used for temperature in _________
 ____________________________________________________________
 to go from C to K…_________________________________
eg)
0C =
25C =
-30C =
-273.15C =
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B. Charles’ Law
 __________________________ (and Joseph
Louis Gay-Lussac) noticed that there was a relationship between the
___________________________
and ____________________ of a gas
 as temperature _______________________, so does the ______________
of the gas molecules
 as the molecules move _____________, they exert ____________ pressure
 the volume of the gas will _______________________________________
until it reaches _____________________________________________
 Charles’ Law states that the _____________________________________
____________________________________________________________
____________________________________________________________
where:
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Example 1
A balloon was inflated at 27C and has a volume of 4.0 L. If it is heated to
57C, what is the new volume? (assume constant pressure)
Example 2
A sample of gas occupies 6.8 L at 110C. What will the final temperature be in
C when the volume is decreased to 5.6 L?
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Chapter 4: Exploring Gas Laws
4.1 The Combined Gas Law
A. Combined Gas Law Calculations
 ________ = standard temperature and pressure
= __________________________________________________
 _________ = standard ambient temperature and pressure
= _________________________________________________
 now we’ll combine Boyle’s Law and Charles’ Law
where:
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Example 1
A weather balloon is filled with H2(g) at 20C and 100 kPa. It has a volume of
7.50 L. It rises to an altitude where the air temperature is -36C and the pressure
is 28 kPa. What is the new volume of the balloon?
Example 2
A large syringe at was filled with 50.0 mL of ammonia gas at STP. If the gas
was compressed to 25.0 mL with a pressure of 210 kPa, what was the final
temperature in C?
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B. Combining Volumes of Gases
 Gay-Lussac analyzed _______________________________________ that
involved _____________
 he studied the _________________ of the gaseous reactants and products
and concluded that the gases combine in ____________________________
____________________________________
 the ________________________________________________________
states that, when gases react, the ____________________ of the gaseous
reactants and products, measured at constant temperature and pressure, are
always in _____________________________________
eg) N2(g) + 3 H2(g)  2 NH3(g)
Example
What volume of nitrogen is used up if 100 mL of ammonia is formed in a
composition reaction?
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4.2 Ideal Gas Law
A. Ideal Gas Law Calculations
this law combines all four variables (__________________________)
into _____________________________________
where:
Example 1
What is the volume of 10.8 mol of oxygen gas at 100.00 kPa and 15.5C?
Example 2
A rigid steel vessel with a volume of 20.0 L is filled with nitrogen gas to a
pressure of 20 000 kPa at 27.0C. What is the number of moles of nitrogen?
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Example 3
What is the pressure exerted by 15.5 g of methane, CH4(g), if it occupies a
volume of 10.0 L at 25C?
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Example 4
What is the mass of hydrogen gas contained in a 4.5 L weather balloon at
25C and 102.0 kPa?
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B. Dalton’s Law of Partial Pressures
 Dalton’s law of partial pressures states that in a
mixture of gases that do
_____________________________________________________, the
_______________________________________ is the ________________
____________________________________________________________
Example
Two gases are pumped into a 32.0 L reaction vessel at 25.0 C one after
another. 6.20 mol of O2(g) is pumped in first, then 8.30 mol of H2(g) is pumped
in. What would the pressure gauge reading be after each gas is pumped in?
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C. Ideal Gases and Real Gases
 for ideal gases we assume that there are no _________________________
_________________________________ between the molecules of the gas
 in real gases, however, there are _________________________ between
the molecules
 we don’t have to worry about considering this in our calculations because
at standard P and T conditions, the molecules are _____________________
and are ____________________________________ they ____________
_____________________________ much with each other
 real gases behave like ideal gases at _______________________________
and __________________________________________
 real gases deviate from ideal gas behaviour at _______________________
________________________________________ and ________________
Review Assignment:
Chemistry 20 Gases Notes
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