Avogadro's Law

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Avogadro's Law

• Equal amounts (in mole) of any gas will occupy
  the same volume at the same temperature and
  pressure.
• Under Standard Temperature and Pressure (STP)
  conditions (1 atm and 0oC), 1 mole of any gas
  will occupy 22.4 dm3 (i.e 22.4 dm3 mol-1)
• n V
• Vm

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Boyles Law

• At constant temperature, the volume of a fixed
  sample of gas is inversely proportional to the
  pressure exerted on the gas
• p1V1 p2V2

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Charles Law

• At constant pressure, the volume of a given mass
  of an ideal gas increases or decreases by the
  same factor as its temperature increases or
  decreases

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Summary

• Boyles Law Inverse relationship
• when P?V? and if P?V?
• Charless Law -- Direct relationship
• when V?T? and if
  V?T?

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Ideal Gas Equation

• PV nRT

where P pressure (PSI, atm, mmHg, kPa) V
volume (dm3, L) n moles of gas (mol) T
temperature (K) R gas constant R 8.314 J K-1
mol-1 if kPa, dm3, K R 0.0821 L atm K-1 mol-1
if atm, L, K
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Try this one

• 3.376g of a gas occupies 2.368 dm3 at 17.60C and
  a pressure of 96.73 kPa.
• How many moles of gas are present?
• What is its molar mass?
• What gas could it be?

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• n PV
• RT
• 96.73 x 2.368
• 8.314 x 290.6
• 0.09481 mol
• M m
• n
• 3.376
• 0.09481
• 35.61 g mol-1