Avogadro’s Law Gas Density

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Avogadros LawGas Density

• Relationships between amounts of gas and volume

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Avogadros Law

• The volume of a gas at constant temperature and
  pressure is proportional to the number of moles
  of gas
• V ? n
• ? means proportional to
• V kn
• V1/n1 V2/n2

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Standard Molar Volume

• The volume of 1.0 mole of any gas at STP is 22.4
  L.
• This is called the standard molar volume.
• The volume of any gas at STP can be calculated if
  the number of moles is known
• V (moles) x 22.4

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Avogadros Law Problems

• One mole of gas at STP has a volume of 22.4 L.
  How many moles of gas are present in a 3.00 L
  container at STP?
• If 0.222 mol of a gas has a volume of 5.13 L.
  How many moles of gas would be present if the
  volume was 7.47 L (at the same temperature and
  pressure)?
• A 21.0 g lump of dry ice (carbon dioxide)
  completely sublimes. The resulting CO2 gas
  occupies a volume of 11.5 L. What would be the
  volume of 1.00 mol of CO2?
• 22.0 g of CO2 occupies a volume of 11.2 L at STP.
  Calculate the volume of 44.0 g of CO2 at STP.

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Density of Gases

• Density mass/volume
• Calculate the density of CH4 at STP
• Assume 1 mole of CH4
• V 22.4 L
• density mass/volume 16/22.4
• 0.714 g/L

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Density of Gases Problems

• Calculate the density of chlorine gas at STP.
• Determine the density of helium gas at STP.
• What is the volume of 0.200 g of hydrogen gas at
  STP?
• How many moles of nitrogen gas can be in a
  balloon with a volume of 6.00 L at STP?