Gases

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Gases
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hang_7e_esp/gam2s2_6.swf
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Section 1 The Gas Laws
1. Use the kinetic-molecular theory to
explain the behavior of gases
2. State, apply, calculate the 3 following
gas laws
a. Boyles Law
b. Charless Law
c. Gay-Lussacs Law
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A. The Kinetic-Molecular Theory
1. Gas particles do NOT attract or repel
2. Gas particles are small virtually no volume
3. Gas particles are in constant, random motion
4. Kinetic energy is transferred during the
elastic collisions

1. All gases have same averagekinetic energy at
   given temp

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B. The Nature of Gases
1. Actual gases do not always obey
the kinetic-molecular theory
2. The KMT is based on 4 factors
a. Temperature (measured in Kelvin) oC
273 K
b. Pressure (measured in atm, kPa, etc.)
1atm 101.3kPa 760 mmHg or torr
c. Volume (measured in liters or mL)
d. Amount of Gas (measured in moles)
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http//www.chem.iastate.edu/group/Greenbowe/sectio
ns/projectfolder/flashfiles/gaslaw/boyles_law_grap
h.html
C. Boyles Law
1. Temperature held CONSTANT
2. Found inverse relationship between pressure
volume
3. P1 V1 P2 V2
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Volume vs- Pressure of a Gas
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P1 V1 P2 V2
Sample Problem 1 If the pressure of helium gas
in a balloon has a volume of 4.0 L at 210 kPa,
what will the pressure be at 2.5 L?
340 kPa
Complete Practice Problems 1 - 5 SHOW YOUR
WORK!!!
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http//www.chem.iastate.edu/group/Greenbowe/sectio
ns/projectfolder/flashfiles/gaslaw/charles_law.htm
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http//www.marymount.k12.ny.us/marynet/06stwbwrk/0
6gas/2slyscharles/2slysflash.html
D. Charless Law
1. Pressure held CONSTANT
2. Found direct relationship between
temperature volume
3. V1 V2
T1
T2
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ns/projectfolder/flashfiles/gaslaw/charles_law.htm
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Temperature vs- Volume of a Gas
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V1 V2
T1
T2
Sample Problem 2 A gas sample at 40 oC
occupies a volume of 2.32 L. If the temperature
is increased to 75 oC, what will be the final
volume?
2.58 L
Complete Practice Problems 6 - 8 SHOW YOUR
WORK!!!
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http//www.marymount.k12.ny.us/marynet/06stwbwrk/0
6gas/1amcslussac/amcsgaylussac.html
E. Gay-Lussacs Law
1. Volume held CONSTANT
2. Found direct relationship between
temperature pressure
3. P1 P2
T1
T2
What would a graph look like for Gay-Lussacs Law?
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P1 P2
T1
T2
Sample Problem 3 The pressure of a gas in a
tank is 3.2 atm at 22 oC. If the temperature
rises to 60oC, what will be the pressure in the
tank?
3.6 atm
Complete Practice Problems 9 - 11 SHOW YOUR
WORK!!!
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Section 2 The Combined Gas Law Avogadros
Principle
1. State, apply, calculate the combined gas
law
2. Relate number of particles and volumes using
Avogadros Principle
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A. The Combined Gas Law
1. Amount of Gas held CONSTANT
2. P1 V1 P2 V2
T2
T1
3. This law combines which 3 laws?
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lloon.html
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Sample Problem 4 A gas at 110 kPa and 30 oC
fills a container at 2.0 L. If the temperature
rises to 80oC and the pressure increases to 440
kPa, what is the new volume?
0.58 L
Complete Practice Problems 12 - 14 SHOW YOUR
WORK!!!
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B. Avogadros Principle
1. Equal volumes of gases at the same
temperature and pressure contains equal
number of particles
2. Molar volume 22.4 L/mol at STP
3. STP (Standard Temp Pressure) Temperature
0 oC or 273 K Pressure 1 atm
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Sample Problem 5 Calculate the volume that
0.881 mol of a gas at STP will occupy.
19.7 L
Complete Practice Problems 15 - 17 SHOW YOUR
WORK!!!
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Section 3 The Ideal Gas Law
1. State, apply, calculate the ideal gas law
2. State, apply, calculate Daltons
Law of Partial Pressure
3. State, apply, calculate Grahams
Law of Effusion
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aw/fr2.1.html
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A. The Ideal Gas Law
1. Contains ALL variables
2. P V n R T

1. WhereP pressure (depends on R)

V volume (liters)
n amount of gas (moles)
R ideal gas constant (depends on pressure)
T temperature (Kelvin)
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R ideal gas constant (depends on pressure)
Pressure R value
atm 0.0821
kPa 8.314
mm Hgtorr 62.4
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Sample Problem 6 Calculate the volume of a gas
at STP with 2.80 moles.
62.8 L
Sample Problem 7 Calculate the moles of a gas
at STP with a volume of 238 L.
10.6 mol
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Sample Problem 8 Calculate the number of moles
of gas contained in a 3.0 L vessel at 27 oC with
a pressure of 1.50 atm.
0.18 mol
Complete Practice Problems 18 - 20 SHOW YOUR
WORK!!!
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B. Daltons Law of Partial Pressure
1. Contains only pressure
2. Where pressure must be in the same units
3. Ptotal P1 P2 P3 . . .
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4. Sample Problem 9 If the total pressure of a
mixture of oxygen nitrogen gases was 820 mmHg,
how much pressure would nitrogen exert if oxygen
had 580 mmHg?
240 mmHg
Complete Practice Problems 21 - 22 SHOW YOUR
WORK!!!
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C. Grahams Law of Effusion
1. Contains rates masses of gases
2. Rate A Mass B
Rate B
Mass A

1. WhereRate is measured in m/s Mass is measured
   in grams

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Sample Problem 8 If neon travels at 400. m/s,
estimate the average speed of butane (C4H10) at
the same temperature.
235 m/s
Sample Problem 9 Chlorine has a velocity of
0.0380 m/s. What is the average velocity of
sulfur dioxide under the same conditions?
0.0400 m/s
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Complete Practice Problems 23 - 24 SHOW YOUR
WORK!!!