WA  What is the pressure in a tank of 2.3 moles of Oxygen gas that has volume of 100 L and a temperature of 5 o C?

Partial pressure of gases in gas mixtures  The pressure of a gas mixture is the sum of the partial pressures pP of the individual gases it is composed of Ex: P air = pP O2 + pP CO2 + pP N2 + pP trace

Composition of air  Which gas produces most of the atmospheric pressure?

Practice 1  A mixture of noble gases He, Ar, Ne, in a fluorescent light tube has a pressure of 2.89 atm. The partial pressure of Helium alone is 0.5 atm. What is the pP of Neon and of Argon if Argon is twice that of Helium?

Practice 2  A noble gas has a pressure of 3.8 atm and consists of He, Ne, Ar with 67%Ar, 25%He and 8%Ne  Calculate the individual pressure of the individual gasses

Practice  A tank contains 257 g of N2 and 35 g of O2 gas at a pressure of 400 kPa. How many moles of N2? How many moles of O2? Total moles in tank? %moles of N2 % moles of O2 What are the partial pressures of N2, O2?

Practice 4 Use the table on your HW sheet to find: the vapor pressure of water at Celsius in _____torr (=mmHg) Celsius in _____ torr

Chapter 14.3 Real Gases

Gas Particles of an “Ideal Gas”  have no volume  are not attracted to each other  Do not undergo a phase change to liquid

Gas Particles of a “Real Gas”  have a volume  are attracted to each other if in a small space  turn into a liquid when compressed or cooled

Diving: breathing air under great pressure  Compressed Air: 78% N2, 21% O2, 1% Other gases Depth of 100 ft: pressure is so high it turns gases into liquids that dissolve in the blood of divers CO2 and O2 are not a problem but if N2 dissolves in the blood it leads to Nitrogen narcosis - interferes with nerve impulses, dizziness, slow reaction Solution: use of Nitroxx air: 50%O2 and 30%-40% N2 some CO2

Decompression Sickness  When a diver surfaces too quickly, dissolved N2 liquid turns back into gas, forming small bubbles, blocking arteries: nausea, pain, vomiting  Solution: slow, gradual ascend with safety stops or  use of decompression chambers

Dive tables in scuba  How to use dive tables How to use dive tables How to use dive tables  decompression sickness decompression sickness decompression sickness

Warm-up PP of gases  The pressure of a 2.0 L Hydrogen/water vapor mixture at 27.8 Celsius is torr. 1. What is the partial pressure of the Hydrogen gas? (use table from HW) 2. How many moles of H2 gas? At 27.8 Celsius water vapor has torr torr – = torr torr torr x kPa = 2.93 kPa 760 torr n= PV = 2.93 x 2.0L = moles n= PV = 2.93 x 2.0L = moles RT 8.31 x RT 8.31 x 300.8

An underground cavern contains 2,356 L methane gas CH4 at a pressure of 150 kPa and a temperature of 315 K. How many moles of CH4 does the cavern contain?  P = 150 kPa  V = 2,356 L  T = 315 K  R = 8.13 L kPa/K mol n = PV =150 kPax 2,356L n = PV =150 kPax 2,356L = moles RT 8.31unit x 315 K

Journal The volume of a gas filled balloon is 30.0 L at 313 K and 153 kPa. What would be the volume at STP? Hint: What is P, T at STP? V1 = 30.0LV2=? T1=313 KT2=273K P1=153 kPaP2=101.3kPa V2=P1 x V1 x T2 =153x30.0x273 = 39.5L P2 x T x 313 P2 x T x 313

Warm-up  What is the volume of 2.3 moles of Helium gas under 5 atm pressure and a temperature of 300K? V=nRT = 2.3 x x 300 = L P5 atm P5 atm