End Show Copyright Pearson Prentice Hall Slide 1 of Properties of Gases In organized soccer, a ball that is properly inflated will rebound faster and travel farther than a ball that is under-inflated. If the pressure is too high, the ball may burst when it is kicked. You will study variables that affect the pressure of a gas. End Show Slide 2 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Compressibility Compressibility is a measure of how much the volume of matter decreases under pressure. Why are gases easier to compress than solids or liquids are? When a person collides with an inflated airbag, the compression of the gas absorbs the energy of the impact. Gases are easily compressed because of the space between the particles in a gas. The distance between particles in a gas is much greater than the distance between particles in a liquid or solid. Under pressure, the particles in a gas are forced closer together. At room temperature, the distance between particles in an enclosed gas is about 10 times the diameter of a particle. End Show Copyright Pearson Prentice Hall Properties of Gases > Slide 4 of Factors Affecting Gas Pressure What are the three factors that affect gas pressure? The amount of gas, volume, and temperature are factors that affect gas pressure. End Show Slide 5 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Factors Affecting Gas Pressure Four variables are generally used to describe a gas. The variables and their common units are pressure (P) in kilopascals volume (V) in liters temperature (T) in kelvins the number of moles (n). End Show Slide 6 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Factors Affecting Gas Pressure Amount of Gas You can use kinetic theory to predict and explain how gases will respond to a change of conditions. If you inflate an air raft, for example, the pressure inside the raft will increase. End Show Slide 7 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Factors Affecting Gas Pressure Collisions of particles with the inside walls of the raft result in the pressure that is exerted by the enclosed gas. Increasing the number of particles increases the number of collisions, which is why the gas pressure increases. End Show Copyright Pearson Prentice Hall Slide 8 of 21 Properties of Gases > 14.1 Factors Affecting Gas Pressure If the gas pressure increases until it exceeds the strength of an enclosed, rigid container, the container will burst. End Show Slide 9 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Factors Affecting Gas Pressure Volume You can raise the pressure exerted by a contained gas by reducing its volume. The more a gas is compressed, the greater is the pressure that the gas exerts inside the container. End Show Copyright Pearson Prentice Hall Slide 10 of 21 Properties of Gases > 14.1 Factors Affecting Gas Pressure When the volume of the container is halved, the pressure the gas exerts is doubled. End Show Slide 11 of 21 Copyright Pearson Prentice Hall Properties of Gases > 14.1 Factors Affecting Gas Pressure Temperature An increase in the temperature of an enclosed gas causes an increase in its pressure. As a gas is heated, the average kinetic energy of the particles in the gas increases. Faster-moving particles strike the walls of their container with more energy. End Show Copyright Pearson Prentice Hall Slide 12 of 21 Properties of Gases > 14.1 Factors Affecting Gas Pressure When the Kelvin temperature of the enclosed gas doubles, the pressure of the enclosed gas doubles. End Show Copyright Pearson Prentice Hall Slide 13 of 21 Section Quiz -or- Continue to: Launch: Assess students understanding of the concepts in Section 14.1 Section Quiz Copyright Pearson Prentice Hall Slide 14 of 21 End Show 14.1 Section Quiz. 1. Compared to liquids and solids, gases are easily compressed because the particles in a gas a.attract each other. b.are spaced relatively far apart. c.are very small. d.repel each other. Copyright Pearson Prentice Hall Slide 15 of 21 End Show 14.1 Section Quiz. 2. Gas pressure is affected by a.temperature, volume, and the amount of the gas. b.temperature, volume, and the molar mass of the gas. c.phase diagram, volume, and the size of the container. d.temperature, phase diagram, and the mass of the gas container. Copyright Pearson Prentice Hall Slide 16 of 21 End Show 14.1 Section Quiz. 3. For gases, the SI units for volume (V), pressure (P), and temperature (T) are, respectively, a.liters, kilopascals, and C. b.liters, kilopascals, and kelvins. c.cm 3, kilopascals, and kelvins. d.liters, atmospheres, and C. Copyright Pearson Prentice Hall Slide 17 of 21 End Show The Gas Laws This hot air balloon was designed to carry a passenger around the world. You will study some laws that will allow you to predict gas behavior under specific conditions, such as in a hot air balloon. How are the pressure, volume, and temperature of a fixed quantity of gas related? Copyright Pearson Prentice Hall Slide 18 of 21 End Show Boyles Law: Pressure and Volume If the temperature is constant, as the pressure of a gas increases, the volume decreases. Boyles law states that for a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure. Copyright Pearson Prentice Hall Slide 19 of 21 End Show Boyles Law: Pressure and Volume Simulation (Virtual lab) and Boyle Law Lab Examine the relationship between gas volume and pressure. Copyright Pearson Prentice Hall Slide 20 of 21 End Show 14.1 for Sample Problem 14.1 INDEX CARD activity (turn in for evaluation) Copyright Pearson Prentice Hall Slide 23 of 21 End Show Charless Law: Temperature and Volume As the temperature of an enclosed gas increases, the volume increases, if the pressure is constant. Charless law states that the volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant. Copyright Pearson Prentice Hall Slide 24 of 21 End Show Charless Law: Temperature and Volume As the temperature of the water increases, the volume of the balloon increases. Copyright Pearson Prentice Hall Slide 25 of 21 End Show Charless Law: Temperature and Volume Simulation (Virtual Lab): Examine the relationship between gas volume and temperature. Copyright Pearson Prentice Hall Slide 26 of 21 End Show 14.2 Copyright Pearson Prentice Hall Slide 27 of 21 End Show 14.2 for Sample Problem 14.2 INDEX CARD activity (turn in for evaluation) Copyright Pearson Prentice Hall Slide 29 of 21 End Show Gay-Lussacs Law: Pressure and Temperature As the temperature of an enclosed gas increases, the pressure increases, if the volume is constant. Gay-Lussacs law states that the pressure of a gas is directly proportional to the Kelvin temperature if the volume remains constant. Copyright Pearson Prentice Hall Slide 30 of 21 End Show Gay-Lussacs Law: Pressure and Temperature When a gas is heated at constant volume, the pressure increases. Copyright Pearson Prentice Hall Slide 31 of 21 End Show Gay-Lussacs Law: Pressure and Temperature A pressure cooker demonstrates Gay-Lussacs Law. Simulation (virtual lab) Examine the relationship between gas pressure and temperature. 14.3 for Sample Problem 14.3 INDEX CARD activity (turn in for evaluation) Copyright Pearson Prentice Hall Slide 35 of 21 End Show The Combined Gas Law The combined gas law describes the relationship among the pressure, temperature, and volume of an enclosed gas. The combined gas law allows you to do calculations for situations in which only the amount of gas is constant. 14.4 for Sample Problem 14.4 INDEX CARD activity (turn in for evaluation) Copyright Pearson Prentice Hall Slide 39 of 21 End Show The Combined Gas Law Weather balloons carry data-gathering instruments high into Earths atmosphere. At an altitude of about 27,000 meters, the balloon bursts. Copyright Pearson Prentice Hall Slide 40 of 21 End Show 14.2 Section Quiz. 1. If the volume of a gas in a container were reduced to one fifth the original volume at constant temperature, the pressure of the gas in the new volume would be a.one and one fifth times the original pressure. b.one fifth of the original pressure. c.four fifths of the original pressure. d.five times the original pressure. Copyright Pearson Prentice Hall Slide 41 of 21 End Show 14.2 Section Quiz. 2. A balloon appears slightly smaller when it is moved from the mountains to the seashore at constant temperature. The best gas law to explain this observation would be a.Gay-Lussacs's Law. b.Graham's Law. c.Boyle's Law. d.Charles's Law. Copyright Pearson Prentice Hall Slide 42 of 21 End Show 14.2 Section Quiz. 3. At 46C and 89 kPa pressure, a gas occupies a volume of L. How many liters will it occupy at 0C and 20.8 kPa? a L b.2.58 L c L d.2.20 L