Chapter 11 Gas Laws

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CHAPTER 11
GAS LAWS
Pages 361-391
7
Stamps
7 warm ups!
BACKGROUND INFORMATION
Air is composed of several kinds of
colorless gases.
 Some gases have color.
Chlorine (Cl2): yellow green
Nitrogen Dioxide (NO2):
brownish-red
Any 1 mole of a gas occupies a
volume of 22.4 L.
KINETIC MOLECULAR THEORY OF GASES
Ideal
Gas: A hypothetical gas that
perfectly fits all assumptions of the
kinetic-molecular model.
Real
gas: A gas that does not
behave according to the
assumptions of the kineticmolecular theory.
KINETIC MOLECULAR THEORY OF GASES





1. Gas Consists of large numbers of tiny particles
that are far apart relative to their size.
2. Collisions between gases are always elastic.
 An elastic collision is one where there is no net
loss of total kinetic energy.
3. Gas particles are in continuous, rapid, random
motion.
4. There are no forces of attraction between gas
particles.
5. The temperature of a gas depends on the average
kinetic energy of the particles.
GASES AND PRESSURE
Pressure: Force per unit area on
a surface
 Equation=
FORCE
AREA
Pressure= area 

Pressure= area 

GASES AND PRESSURE
GASES AND PRESSURE
Different
units for measuring
pressure:
(need to memorize!)
1 atm
760 mmHg
101.3 kPa
101300 Pa
760 torr
14.7 lb/in2
CONVERTING PRESSURE
745mmHg=_________________Kpa
16.5atm= __________________lb/in2
11.3 lb/in2=_________________Kpa
100.7Kpa=__________________atm
Barometer:
Instrument
used to measure pressure.
TEMPERATURE CONVERSIONS
Temperature:
Kelvin system:
K=°C+273
-16°C=__________K
8.7°C=___________K
212K=__________°C
0K=_____________°C
Standard
Temperature and
Pressure (STP):
Temperature: 273 K
Pressure: 1 atm
760 mmHg
101.3 kPa
101300 Pa
760 torr
14.7 lb/in2
DALTON’S LAW OF PARTIAL PRESSURE


The sum of the partial pressures of all the
components in a gas mixture is equal to the total
pressure of a gas mixture.
Equation: P1 + P2 + P3 + ……. = PTotal
DALTON’S LAW OF PARTIAL PRESSURE
EXAMPLES

A person using an oxygen mask is breathing air
with 33% oxygen. What is the partial pressure of
oxygen with the air pressure in the mask is
110Kpa?
DALTON’S LAW OF PARTIAL PRESSURE
EXAMPLES

What is the atmospheric pressure if the partial
pressure of nitrogen, oxygen and argon are
604.5mmHg, 162.8mHg, and 0.5mmHg,
respectively?
DALTON’S LAW OF PARTIAL PRESSURE
EXAMPLES
•
Oxygen gas from the decomposition of potassium
chlorate was collected by water displacement. The
barometric pressure and the temperature during the
experiment were 731.0 torr and 20.0C. What was the
partial pressure of the oxygen collected? (Hint: Use
Table A-8 in your text!)
PRESSURE AND VOLUME: BOYLE’S LAW

The volume of a gas is indirectly proportional to
the Pressure (@ S.T)

Equation:

Visually:
P1V1 = P2V2
PRESSURE AND VOLUME: BOYLE’S LAW
EXAMPLES

A gas has an initial volume of 242cm3 at a
pressure of 87.6Kpa, what is the volume if the
pressure changes to standard pressure?
PRESSURE AND VOLUME: BOYLE’S LAW
EXAMPLES

A gas at a pressure of 608mmHg is held in a
container with a volume of 545cm3. The volume
of the container is then increased to 1065cm3
without a change in temperature. Calculate the
new pressure of the gas
VOLUME AND TEMPERATURE: CHARLES’
LAW

The volume of a gas is directly proportional to
the temperature (@ S.P).

Equation: V1
= V2
T1 T2

Visually:
VOLUME AND TEMPERATURE: CHARLES’
LAW



Animations
http://www.marymount.k12.ny.us/marynet/06stw
bwrk/06gas/1esepcharles/esepcharles.html
http://www.marymount.k12.ny.us/marynet/06stw
bwrk/06gas/2slyscharles/2slysflash.html
VOLUME AND TEMPERATURE: CHARLES’
LAW - EXAMPLES
•
If 20.0L of Oxygen gas are cooled from 100C to 0C.
what is the new volume?
VOLUME AND TEMPERATURE: CHARLES’
LAW - EXAMPLES
•
A gas can be used as a thermometer. IF it is known
that the sample of gas has a volume of 1.00L at 255K,
what is the temperature if the volume of the same gas
sample is changed to 0.45L
PRESSURE AND TEMPERATURE: GAYLUSSAC’S LAW
The pressure of a gas is directly proportional to
the temperature (@ constant volume).
 Equation:

PRESSURE AND TEMPERATURE: GAYLUSSAC’S LAW - EXAMPLES
•
The gas in a container is at a pressure of 3.00 atm at
25ºC. Directions on the container warn the used not to
keep it in a place where the temperature exceeds 52ºC.
What would the gas pressure in the container be at a
52ºC?
PRESSURE AND TEMPERATURE: GAYLUSSAC’S LAW - EXAMPLES
•
At 120.0ºC the pressure of a sample of nitrogen is 1.07
atm. What will the pressure be at 205ºC, assuming
constant volume?
COMBINED GAS LAW


Incorporates both Boyle’s and Charles’ laws. It
relates pressure, volume and temperature.
Equation:
P1V1 = P2V2
T1
T2
COMBINED GAS LAW
EXAMPLES

A gas has a volume of 10.0cm3 measured at
75.6Kpa and 60.0C, what is the new volume if
conditions change to STP?
COMBINED GAS LAW
EXAMPLES

A gas that had a volume of 955cm3 measured at
58C and 108.0Kpa, what will be the new volume
if the conditions change to 76.0C and 123.0Kpa?
GAY-LUSSAC’S LAW OF COMBINING
VOLUMES OF GASES

at constant _______________ and
_________________, the _______________ of
gaseous reactants and producs can be expressed
as _____________ of _________________
_____________ ________________.
Animation
 http://www.marymount.k12.ny.us/marynet/06stw
bwrk/06gas/1amcslussac/amcsgaylussac.html

VOLUME AND MOLES: AVAGADRO’S LAW



The volume of a gas is _____________proportional
to the number of moles of that gas (@ S.T).
Equation:
An anmimation:
http://www.marymount.k12.ny.us/marynet/06stw
bwrk/06gas/2lpimavogdro/2lpimavogadro.html
VOLUME AND MOLES: AVAGADRO’S LAW
EXAMPLES
Suppose we have a 12.2 L sample containing 0.50 moles
of oxygen gas at a pressure of 1 atm and a
temperature of 25 C. If all of this oxygen is converted
to ozone, O3, at the same temperature and pressure,
what will be the volume of ozone formed?
VOLUME AND MOLES: AVAGADRO’S LAW
EXAMPLES
•
Consider two samples of nitrogen gas. Sample one
contains 1.5 moles of nitrogen and has a volume of 36.7
L at 25 C and 1 atm. Sample 2 has a volume of 16.5 L at
25 C and 1 atm. Calculate the number of moles of
nitrogen in sample 2.
GAS STOICHIOMETRY:


Standard molar volume of a gas: The volume
occupied by ____________ ___________ of a gas at
STP has been found to equal
______________________.
Example: What volume does 0.0685 mol of gas
occupy at STP?
GAS STOICHIOMETRY:
EXAMPLE

Propane, C3H8, is a gas that is sometimes used as
a fuel for cooking and heating. It undergoes a
combustion reaction. What will be the volume of
oxygen required for the complete combustion of
0.350L of propane?
THE IDEAL GAS LAW
PV=nRT
Where
P=
V=
n=
R=
T=
THE IDEAL GAS LAW
EXAMPLES
•
What pressure will be exerted by .622 mol of a gas
contained in 9.22L at 16C. Find pressure in Kpa.
THE IDEAL GAS LAW
EXAMPLES
•
How many moles of a gas will occupy a 486cm3 flask at
10.C and 66.7 Kpa?
THE IDEAL GAS LAW
EXAMPLES
What volume will be occupied by .684mol of gas at
99.4Kpa and 9C?
DIFFUSION AND EFFUSION

Diffusion:

Effusion:
Animation:
 http://www.marymount.k12.ny.us/marynet/06stw
bwrk/06gas/2hdkrdiffusion/2hdkrdiffusion.html

DIFFUSION AND EFFUSION

Graham’s Law: Rates of _________________ of
gases at the same _____________ and
______________ are inversely proportional to the
_______________ ____________ of their
________________ ________________.
DIFFUSION AND EFFUSION
EXAMPLES

Compare the rates of effusion of hydrogen and
oxygen at the same temperature and pressure.
DIFFUSION AND EFFUSION
EXAMPLES

Compare the rate of effusion of carbon dioxide
with that of hydrogen chloride at the same
temperature and pressure.
Animation Summary:
 http://www.mhhe.com/physsci/chemistry/essentia
lchemistry/flash/gasesv6.swf

Web Quest
 http://www.chemheritage.org/EducationalService
s/webquest/blimp.htm

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