Gas laws

• What is vapor in relation to liquid?

  Co-existence of gas in equilibrium with liquid
• What is the critical temperature?

  Temperature above which liquid state is impossible
• How are pressure, volume, and temperature related in gases?

  They are related in a consistent manner
• What are the three main gas laws?

  • Boyle’s law
  • Charles’s law
  • Gay-Lussac’s law

  
• What does Boyle's law state?

  Volume varies inversely with pressure at constant temperature
• What is the formula for Boyle's law?

  $PV=$$K$ (at constant temperature)
• What happens to volume as altitude increases?

  Volume expands in enclosed spaces
• What can happen if a diver holds their breath during ascent?

  Can cause barotrauma or gas embolism
• What is the estimated gas expansion at 2.5 km altitude?

  Up to 30% for closed gas volume
• What is barodontalgia?

  Pain in teeth due to pressure changes
• What does Charles's law state?

  Volume is proportional to temperature at constant pressure
• What is the formula for Charles's law?

  $V/T=$$K$ (at constant pressure)
• How does warming inspired gases affect their volume?

  Increases volume from 20°C to 37°C

  
• What does Gay-Lussac's law state?

  Pressure is directly proportional to temperature at constant volume
• What is the formula for Gay-Lussac's law?

  $P/T=$$K$ (at constant volume)
• How can gas laws be used to calculate changes in variables?

  • Two variables known
  • Third variable assumed constant
  • Calculate changes when one alters
• What are the equivalent values for pressure units?

  • 1 atm = 1 bar = 101.3 kPa = 760 mmHg = 760 Torr = 1033.2 cmH2O = 14.7 PSI
• What does Avogadro's law state?

  Equal volume of gas contains same number of molecules
• What volume does 1 mole of gas occupy at standard conditions?

  22.4 liters at 1 atm and 0°C
• What is the ideal gas law formula?

  $PV=$$nRT$
• What does Henry's law state about gas solubility?

  Gas dissolved is proportional to partial pressure
• How does temperature affect gas solubility?

  Higher temperatures reduce gas solubility
• Why is Henry's law important for anesthetic gases?

  It explains their physiological behavior
• What does Dalton's law state about gas mixtures?

  Pressure of gas is independent of others
• How does Dalton's law relate to vapor pressure?

  Vapor pressure is unaffected by ambient pressure
• What is the nature of the gas laws described?

  They refer to a theoretical "ideal" gas
• When are gas laws accurate?

  When applied to gases above critical temperature
• What is the boiling point of oxygen?

  -183°C
• What is the critical temperature of oxygen?

  -119°C
• How does Boyle's law apply to oxygen cylinders?

  Pressure gauge indicates remaining volume
• What inaccuracies may arise with Boyle's law?

  Large temperature changes affect accuracy
• How can oxygen be stored in cylinders?


  Under pressure or in cylinder banks
• What happens when liquid oxygen warms?

  Makes a large volume of oxygen gas
• What is a vacuum insulated evaporator (VIE)?

  Container designed to store liquid oxygen
• What is the boiling point of nitrous oxide?

  -88.6°C
• What is the critical temperature of nitrous oxide?

  +36°C
• How does the pressure gauge for nitrous oxide behave?

  Always reads around 52 bar at room temperature
• How do you determine the quantity of nitrous oxide left in a cylinder?

  Weigh cylinder and subtract empty weight
• What is the filling ratio for nitrous oxide cylinders in the UK?

  0.75, reduced to 0.67 in hotter climates
• What is the trade name for 50% oxygen and 50% nitrous oxide?

  BOC Medical