Gases

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Gases

• Chapter 5

• Outline
• Properties of Gases
• Pressure
• Gas Laws
• Boyles Law
• Charles Law
• Avogadros Law
• Ideal Gas Law
• Daltons Law
• Gas Stoichiometry
• Kinetic Molecular Theory
• Grahams Law
• Real Gases

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How do gases create pressure?
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Chapter 5 Examples Gas Pressure

• Prove that 1.00 atm is equal to 29.9 in Hg.

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Boyles Law
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Chapter 5 Examples Gas Laws

• What is the volume of 1.00 moles of an ideal gas
  at STP?

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Molar Volume
Tro Chemistry A Molecular Approach, 2/e
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How does molar mass affect gas density?
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How does temperature affect gas density?
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Chapter 5 Examples Gas Laws

• In an industrial process, 500. L of hydrogen gas
  initially at 101 kPa and 22 C is compressed into
  a vessel of volume 15.0 L and heated to 420 C.
  What is its final pressure?

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Chapter 5 Examples Gas Laws

• The volatile organic compound geraniol, a
  component of oil of roses, is used in perfumery.
  The density of the vapor at 260 C is 0.480 g/L,
  when the pressure is 103 torr. What is the molar
  mass of geraniol?

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Chapter 5 Examples Gas Laws

• A 32.5 mole sample of a gas is injected into an
  evacuated, constant-volume container at 22 C and
  atmospheric pressure. What amount of moles of gas
  must be released, if the temperature is raised to
  212 C at constant pressure and some of the gas
  is allowed to escape during the heating?

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Collecting Gas by Water Displacement
Tro Chemistry A Molecular Approach, 2/e
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Chapter 5 Examples Gas Laws

• Automobile air bags are filled when sodium azide,
  NaN3, decomposes into elemental sodium and
  nitrogen gas. If 10.0 g of sodium azide
  decompose, the nitrogen gas is collected over
  water at 18 C (vapor pressure of water at 18 C
  is 15.5 torr) and the barometric pressure is 747
  mmHg. What is the partial pressure of dry
  nitrogen gas in the sample?

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Chapter 5 Examples Gas Laws

• Haloethane, C2HBrClF3, is a nonflammable,
  nonexplosive, nonirritating gas that is commonly
  used as an inhaled anesthetic. If 15.0 g
  haloethane vapor is mixed with 23.5 g of oxygen
  gas, and the total pressure of the mixture is 855
  mmHg, what is the mole fraction and partial
  pressure of each gas?

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Chapter 5 Examples Gas Laws

• A mixture of argon and nitrogen gases has a
  density of 1.413 g/L at STP. What is the mole
  fraction of each gas?

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Chapter 5 Examples Gas Stoichiometry

• Calculate the volume of acetylene, C2H2, produced
  at 25 C and 1.00 atm when 10.0 g of calcium
  carbide reacts completely with water in the
  unbalanced reaction
• CaC2(s) H2O (l) ? Ca(OH)2 (aq) C2H2 (g)

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Chapter 5 Examples Gas Stoichiometry

• What mass of titanium(IV) oxide is produced from
  the reaction of 200. L of titanium(IV) chloride
  and excess water at 500 kPa and 30 C? Given the
  unbalanced equation
• TiCl4 (g) H2O (l) ? TiO2 (g) HCl (g)
  
  
  
  

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Chapter 5 Examples Gas Stoichiometry

• If you have 355 L of hydrogen gas at 25 C and
  542 mmHg and combine it with excess nitrogen gas
  in the presence of an iron catalysis at 500 C,
  what volume of ammonia gas will be collected
  under the same conditions?

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Chapter 5 Examples Gas Stoichiometry

• A mixture of carbon monoxide and oxygen gas in a
  2.89 L container at 907 K has a total pressure of
  2.75 atm. After time, the pressure falls to 2.24
  atm due to carbon dioxide formation. How many
  grams of carbon dioxide are formed?

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Chapter 5 Examples Gas Stoichiometry

• Dichlorine monoxide is a powerful oxidizing agent
  that is used to bleach wood pulp and to treat
  municipal water supplies. It is made by the
  reaction
• SO2 (g) 2 Cl2 (g) ? SOCl2 (g) Cl2O (g)
• If you put sulfur dioxide in a flask at 125 mmHg
  at 22 C, and add chlorine gas to this same
  flask, what should the chlorine gas partial
  pressure be in order to have the correct
  stoichiometric ratio of sulfur dioxide to
  chlorine gases?

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Chapter 5 Examples Gas Stoichiometry

• A 3.0 L bulb containing helium gas at 145 mmHg is
  connected to a 2.0 L bulb containing argon gas at
  355 mmHg by a valve. Calculate the partial
  pressure after the valve between the flasks is
  opened.

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Maxwell-Boltmann DistributionEffect of
Temperature on the Velocity of a Gas
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Effect of Molar Mass on Molecular Speed
Tro Chemistry A Molecular Approach, 2/e
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Chapter 5 Examples Gas Speed

• Calculate the rms speed of oxygen molecules at 25
  C.

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The four most common gases in the atmosphere are
N2, O2, Ar, and CO2. Assuming all gases are in
containers of equal size, temperature, and
pressure, which gas has the highest density?
Chapter 5 Examples Gas Density

1. All have the same density
2. N2
3. O2
4. Ar
5. CO2

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The four most common gases in the atmosphere are
N2, O2, Ar, and CO2. Assuming all gases are in
containers of equal size, temperature, and
pressure, which gas has the highest density?
Chapter 5 Examples Gas Density

1. All have the same density
2. N2
3. O2
4. Ar
5. CO2

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Mean Free Path
Tro Chemistry A Molecular Approach, 2/e
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Effusion
Tro Chemistry A Molecular Approach, 2/e
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Chapter 5 Examples Gas Effusion

• Why does it take several minutes for a reaction
  to occur between ammonia and hydrogen chloride
  gases in the same tube? Each gas is added to the
  opposite end of a tube and the tube is then
  sealed with cotton plugs.
• NH3 (g) HCl (g) ? NH4Cl (s)

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Chapter 5 Examples Gas Effusion

• A sample of pure methane, CH4, is found to effuse
  through a porous barrier in 1.50 minutes. Under
  the same conditions an equal number of molecules
  of gas X effuse through the barrier in 4.73
  minutes. What is the molar mass of gas X?

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How does the ideal gas law change for a real gas?
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Under what conditions would Cl2 gas be the least
ideal?
Chapter 5 Examples Real Gases

• High pressure and low temperature
• High pressure and high temperature
• Low pressure and high temperature
• Low pressure and low temperature

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Under what conditions would Cl2 gas be the least
ideal?
Chapter 5 Examples Real Gases

• High pressure and low temperature
• High pressure and high temperature
• Low pressure and high temperature
• Low pressure and low temperature

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