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DO NOW: A student fills 2 identical balloons at STP with nitrogen and oxygen gases separately. Which balloon has more molecules? The oxygen above is then cooled to 135K. What pressure is exerted by the oxygen?.
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DO NOW: A student fills 2 identical balloons at STP with nitrogen and oxygen gases separately. Which balloon has more molecules?The oxygen above is then cooled to 135K. What pressure is exerted by the oxygen?
Aim: How is the pressure exerted by a mixture of gases different from the pressure of one gas?
Dalton’s Law of Partial Pressure • Partial Pressure—the pressure of one gas in a mixture of gases. • The sum of the partial pressures of the gases in a mixture is equal to the total pressure of the mixture. • Formula: PT = p1 + p2 + p3 +…
Example #1 • A mixture of gases contains 3 gases. Gas A exerts a partial pressure of 1.2 atm, Gas B exerts 0.3 atm, and Gas C exerts 0.8 atm of pressure. What is the total pressure of the gaseous mixture? • PT = 1.2 atm + 0.3 atm + 0.8 atm = 2.3 atm
Vapor Pressure • The pressure of the gas over a liquid in a sealed container. • Vapor pressure of a liquid increases as temperature increases. • Boiling Point—point at which vapor pressure equals atmospheric pressure.
As you increase kinetic energy, the forces holding some of the liquid together get enough energy to break apart and become a gas.There is an increase in vapor pressure as the forces are breaking.Table H also shows you which liquids are stronger (harder to break apart).
Compare propanone and ethanoic acid at 50ºC. • Propanone exerts more vapor pressure. That means its IMFs are weaker and break faster which means it turns into a gas faster.
As the temperature of liquid H2O in a closed system decreases, the vapor pressure • decreases (2) increase (3) remains the same
If the pressure on the surface of propanone in the liquid state is 90 kPa, the liquid will boil at about • 0°C (2) 55°C (3) 80°C (4) 100°C
What is the vapor pressure of a liquid at its normal boiling temperature? • 1 atm (2) 2 atm (3) 273 atm (4) 760 atm
Which property of a sample of mercury is different at 320K than at 300K? (1) atomic mass (3) vapor pressure (2) atomic radius (4) melting point