Gay-Lussac's Law

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Gay-Lussac's Law
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Joseph-Louis Gay-Lussac

• In the early 1800s, Gay-Lussac
• ascended to a height of
• approximately 23,000 ft in a hot
• air balloon to study variations in
• the Earth's electro-magnetic
• intensity relative to altitude. On
• this flight, he experienced the
• effects of oxygen deprivation but
• still managed to collect air
• samples at over 20,000 ft, study
• the variation of pressure and
• temperature, and continue his
• observations on electro-
• magnetism.

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What is Gay-Lussacs Law?

• Gay-Lussac's Law states
• that the pressure of a
• sample of gas at constant
• volume, is directly
• proportional to its
• temperature in Kelvin.

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Mathematically Gay-Lussacs Law can beexpressed
as P1 P2 T1 T2 P1 T2 P2 T1

• P1 is the initial pressure
• T1 is the initial temperature (in Kelvin)
• P2 is the final pressure
• T2 is the final temperature (in Kelvin)

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Gay-Lussacss Law Practice Problems

• A tank of gas has a pressure of 2.75 atm at 20C.
  What will be the new pressure in the tank if its
  temperature is increased to 100C?
• P1 T2 P2 T1
• P1
• T1
• P2
• T2

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• A gas system has initial pressure of 793
• kPa and temperature of 34.5C If the
• pressure changes to 446 kPa, what will the
• resultant temperature be in K?
• P1 T2 P2 T1
• P1
• T1
• P2
• T2

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COMBINED GAS LAW

• The combined gas law is a combination of
• Boyle's Law and Charles's Law hence its
• name the combined gas law. In the
• combined gas law, the volume of gas is
• directly proportional to the absolute
• temperature and inversely proportional to
• the pressure.

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Mathematically, Combined Gas Law can be
expressed as P1V1 P2V2
T1 T2P1V1 T2 P2V2 T1

• P1 is the initial pressure
• V1 is the initial volume
• T1 is the initial temperature (in Kelvin)
• P2 is the final pressure
• V2 is the final volume
• T2 is the final temperature (in Kelvin)

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Combined Gas Law Practice Problems

• A sample of gas occupies a volume of 75 mL at a
  pressure of 725 mmHg and a temperature of 18C.
  What volume would this sample of gas occupy at
  800 mmHg and 298K?
• P1V1 T2 P2V2 T1
• P1
• V1
• T1
• P2
• V2
• T2

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• A sample of gas occupies a volume of 3.75 L at a
  pressure of 1.15 atm and a temperature of 25C.
  At what
• temperature will the sample of gas occupy 4
  L at a pressure of 1 atm?
• P1V1 T2 P2V2 T1
• P1
• V1
• T1
• P2
• V2
• T2