Transcript CHM 111 CHAPTER 6-A The Ideal Gas Law © 2012 by W. W.

CHM 111
CHAPTER 6-A
The Ideal Gas Law
© 2012 by W. W. Norton & Company
Gas Pressure
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Gas Pressure
•
Units of pressure:
atmosphere (atm)
mm Hg (760 mm Hg = 1 atm)
Pressure is force exerted per
unit area
Pa (kg/ms2, 101,325 Pa = 1 atm)
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Boyle’s Law
•
Pressure–Volume Law (Boyle’s Law):
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Boyle’s Law
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Boyle’s Law
•
Pressure–Volume Law (Boyle’s Law):
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Boyle’s Law
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Pressure–Volume Law (Boyle’s Law):
V  1/P
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Charles’ Law
•
Temperature–Volume Law (Charles’ Law):
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Charles’ Law
•
Temperature–Volume Law (Charles’ Law):
VT
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Avogadro’s Law
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The Volume–Amount Law (Avogadro’s Law):
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Avogadro’s Law
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The Volume–Amount Law (Avogadro’s Law):
Vn
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The Ideal Gas Law
•
Ideal gases obey an equation incorporating the laws
of Charles, Boyle, and Avogadro.
PV=nRT
Where R is the combined proportionality constant.
The gas constant, R = 0.08206 L·atm·K–1·mol–1
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Ideal Gas Law
•
What volume does 1 mole of methane gas (CH4)
occupy at standard temperature and pressure
(1.00 atm and 273.15 K)?
•
What volume does 1 mole of carbon dioxide gas
occupy under the same conditions?
•
What is the volume occupied by 7.40 g of CO2 at
STP?
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Ideal Gas Law
•
Oxygen gas is normally sold in 49.0 L steel containers
at a pressure of 150.0 atm. How many moles (n) of
oxygen does one container hold at 20oC?
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What volume would the gas occupy if the pressure
was reduced to 1.02 atm and the temperature raised
from 20oC to 35oC?
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Ideal Gas Law
•
An inflated balloon with a volume of 0.55 L at sea
level, where the pressure is 1.0 atm, is allowed to
rise to a height of 6.5 km, where the pressure is
about 0.40 atm. Assuming that the temperature
remains constant, what is the final volume of the
balloon?
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The Ideal Gas Law
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Sulfur hexafluoride (SF6) is a colorless, odorless,
very unreactive gas. Calculate the pressure (in
atm) exerted by 1.82 moles of the gas in a steel
vessel of volume 5.43 L at 69.5°C.
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Dalton’s Law of Partial Pressures
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Dalton’s Law of Partial Pressures
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The Partial Pressure (Px) of gas X in a mixture of gases is
the pressure that gas X would exert if it alone occupied the
container.
•
When calculating partial pressure, use the ideal gas law and
ignore other gases in the container.
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Dalton’s Law of Partial Pressures
•
In a mixture of gases the total pressure, Ptot, is the sum of
the partial pressures, Px, of the gases:
Ptotal   Px
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Dalton’s law allows us to work with mixtures of gases.
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