Lecture Presentation Chapter Gases Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter Gases Respiratory therapists assess and treat a range of patients They perform a variety of diagnostic tests, including measuring • • breathing capacity concentrations of oxygen and carbon dioxide in a patient’s blood, as well as blood pH General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter Readiness Key Math Skills • Solving Equations (1.4D) Core Chemistry Skills • • • • • Using Significant Figures in Calculations (2.3) Writing Conversion Factors from Conversion Equalities (2.5) Using Conversion Factors (2.6) Using Molar Mass as a Conversion Factor (7.5) Using Mole–Mole Factors (7.6) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 8.1 Properties of Gases Generally molecules with fewer than five atoms from the first two periods in the periodic table are gases at room temperature In addition, the following are also gases: He • H2, N2, O2, F2, and Cl2 • oxides of the nonmetals on the upper-right corner of the periodic table: CO, NO2, SO2, and SO3 • H CO 2, NO, C N O F S Cl Ar Ne Kr Xe noble gases Rn Learning Goal Describe the kinetic molecular theory of gases and the units of measurement used for gases General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Kinetic Molecular Theory A gas consists of small particles that move randomly with high velocities have very small attractive (or repulsive) forces between molecules occupy a much larger volume than the volume of the molecules alone are in constant motion, moving rapidly in straight lines have a Kelvin temperature proportionate to the average kinetic energy of the molecules Gas particles which move in straight lines within a container, exert pressure when they collide with the walls of the container General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Properties That Describe a Gas Gases are described in terms of four properties: pressure (P), volume (V), temperature (T), and amount (n) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Volume The volume of a gas • is the same as the volume of the container it occupies • • is usually measured in liters or milliliters increases with an increase in temperature at a constant pressure Gas particles which move in straight lines within a container, exert pressure when they collide with the walls of the container General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Temperature The temperature of a gas relates to the average kinetic energy of the molecules and is measured in the Kelvin (K) temperature scale When the temperature of a gas is • decreased, the molecules have fewer collisions • increased, the molecules have more collisions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Pressure Pressure is a measure of the gas particle collisions with sides of a container and is measured in units of • millimeters of mercury, mmHg or torr • atmospheres, atm • pascals, Pa, or kilopascals, kPa • pounds per square inch, psi Gas particles in the air exert pressure on us called atmospheric pressure General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Barometers Measure Pressure A barometer • measures the pressure exerted by the gases in the atmosphere • indicates atmospheric pressure as the height in mm of the mercury column 760 mmHg = atm = 760 Torr The barometer was invented by Evangelista Torricelli, at exactly atm the barometer tube measures exactly 760 mm high General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Partial Pressure The partial pressure of a gas is the pressure that each gas in a mixture would exert if it were by itself in the container Core Chemistry Skill Calculating Partial Pressure General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Dalton’s Law of Partial Pressures Dalton’s law of partial pressures indicates that • • pressure depends on the total number of gas particles, not on the types of particles the total pressure exerted by gases in a mixture is the sum of the partial pressures of those gases PT = P1 + P2 + P3 + General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Total Pressure For example, at STP, mole of a pure gas in a volume of 22.4 L will exert the same pressure as mole of a gas mixture in 22.4 L Gas mixtures 1.0 mole N2 0.4 mole O2 0.5 mole O2 0.6 mole He 0.3 mole He 1.0 mole 0.2 mole Ar 1.0 mole 1.0 atm General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake 1.0 atm 1.0 atm © 2016 Pearson Education, Inc Total Pressure The air we breathe • • is a mixture of different gases contains mostly N2 and O2, and contains small amounts of other gases What we call the atmospheric pressure is actually the sum of the partial pressures of the gases in the air General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Guide to Solving for Partial Pressure General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solving for Partial Pressure A scuba tank contains O2 with a pressure of 0.450 atm and He at 855 mmHg What is the total pressure in mmHg in the tank (volume and temperature are constant)? STEP Write the equation for the sum of the partial pressures Ptotal = PO + PHe STEP Rearrange the equation to solve for the unknown pressure Convert units to match Ptotal = PO + PHe General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solving for Partial Pressure A scuba tank contains O2 with a pressure of 0.450 atm and He at 855 mmHg What is the total pressure in mmHg in the tank (volume and temperature are constant)? STEP Substitute known pressures and calculate Ptotal the unknown partial pressure = PO2 + PHe Ptotal = 342 mmHg + 855 mmHg = 1.20 x 10 mmHg General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check For a deep dive, a scuba diver uses a mixture of helium and oxygen with a pressure of 8.00 atm If the oxygen has a partial pressure of 1280 mmHg, what is the partial pressure of the helium (volume and temperature are constant)? A 520 mmHg B 2040 mmHg C 4800 mmHg General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution For a deep dive, a scuba diver uses a mixture of helium and oxygen with a pressure of 8.00 atm If the oxygen has a partial pressure of 1280 mmHg, what is the partial pressure of the helium (volume and temperature are constant)? STEP Write the equation for the sum of the partial pressures Ptotal = PO + Phe STEP Rearrange the equation to solve for the unknown pressure Convert units to match PHe = Ptotal − PO General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake ì â 2016 Pearson Education, Inc Solution For a deep dive, a scuba diver uses a mixture of helium and oxygen with a pressure of 8.00 atm If the oxygen has a partial pressure of 1280 mmHg, what is the partial pressure of the helium (volume and temperature are constant)? STEP Substitute known pressures and calculate the unknown partial pressure PHe = 6080 mmHg – 1280 mmHg = 4800 mmHg or 4.80 × 10 mmHg The answer is C, 4800 mm Hg General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Blood Gases • In the lungs, O2 enters the blood, while CO2 from the blood is released • In the tissues, O2 enters the cells, which releases CO2 into the blood General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Blood Gases In the body, • O2 flows into the tissues because the partial pressure of O2 is higher in blood and lower in the tissues • CO2 flows out of the tissues because the partial pressure of CO2 is higher in the tissues and lower in blood General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Partial Pressures in Blood Partial Pressures in Blood and Tissue General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Gas Exchange During Breathing General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Concept Map, Gas Laws General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... high General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Units of Pressure General, Organic, and Biological Chemistry: Structures. .. dense than mercury General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life,... outside General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Guide to Using Gas Laws General, Organic, and Biological Chemistry: Structures