Chapter 13 Temperature & the Ideal GasSlide 2TemperatureSlide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Temperature ScalesSlide 14Slide 15Slide 16Slide 17Thermal Expansion of Solids and LiquidsSlide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Molecular Picture of a GasSlide 35Slide 36Slide 37Slide 38Absolute Temperature and the Ideal Gas LawSlide 40Slide 41Slide 42Slide 43Slide 44Slide 45Kinetic Theory of the Ideal GasSlide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Chapter 13 Temperature & the Ideal GasMFMcGraw Ch13c-Temperature-Revised-4/25/10 2Chapter 13: Temperature & the Ideal Gas •Temperature•Temperature scales•Thermal expansion of solids and liquids•Molecular picture of a gas•Absolute temperature and the ideal gas law•Kinetic theory of the ideal gas•Collisions between gas moleculesMFMcGraw Ch13c-Temperature-Revised-4/25/10 3TemperatureHeat is the flow of energy due to a temperature difference. Heat always flows from objects at high temperature to objects at low temperature.When two objects have the same temperature, they are in thermal equilibrium.MFMcGraw Ch13c-Temperature-Revised-4/25/10 4The Zeroth Law of ThermodynamicsIf two objects are each in thermal equilibrium with a third object, then the two objects are in thermal equilibrium with each other.MFMcGraw Ch13c-Temperature-Revised-4/25/10 5Thermodynamics“Thermodynamics is a funny subject. The first time you go through it, you don’t understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don’t understand it, but by that time you are so used to it, it doesn’t bother you any more.”- Arnold SommerfeldThermodynamics is the scientific study of work, heat, and the related properties of chemical and mechanical systems.MFMcGraw Ch13c-Temperature-Revised-4/25/10 6Temperature MeasurementRequirement: A substance that exhibits a measureable change in one of its physical properties as the temperature changes. Examples:Volume change with temperature is a common physical property used for the measurement of temperatureThe change of electrical resistance with temperature is also used to measure temperature.MFMcGraw Ch13c-Temperature-Revised-4/25/10 7 Not a Good Temperature Measurement InstrumentMFMcGraw Ch13c-Temperature-Revised-4/25/10 8Mercury ThermometerA mercury-in-glass thermometer, invented by German physicist Daniel Gabriel Fahrenheit.Bulb – reservoir for the thermometric liquidStem – glass capillary tube through which the mercury or organic liquid fluctuates with changes in temperatureScale – the scale is graduated in degrees, fractions or multiples of degreesContraction Chamber– an enlarged capillary bore which serves to reduce a long length of capillary, or prevent contraction ofthe entire liquid column into the bulbExpansion Chamber– an enlargement of the capillary bore at the top of the thermometer to prevent build up of excessivepressures in gas-filled thermometershttp://www.omega.com/Temperature/pdf/INTRO_GLASS_THERM.pdfMFMcGraw Ch13c-Temperature-Revised-4/25/10 9Temperature CalibrationCelsius and Fahrenheit are two different temperature scales but they are calibrated to the same reference points.The two scales have different sized degree units and they label the steam point and the ice point with different temperature values.The “Zero” values on both scales were picked for convenience and can cause problems.MFMcGraw Ch13c-Temperature-Revised-4/25/10 10Temperature MeasurementCalibration This process ensures the accuracy of the measurement. It requires the availability of a repeatable set of states of matter. The boiling point of water and the freezing point of water are two examples. TransferabilityThe calibration needs to be transferable to other measuring instruments. StandardsThere needs to be agreed upon calibration procedures to allow transferability.MFMcGraw Ch13c-Temperature-Revised-4/25/10 11Temperature ScaleAnders Celsius devised the Celsius scale. This was published in The origin of the Celsius temperature scale in 1742.Celsius originally defined his scale "upside-down”• boiling point of pure water at 0 °C and • the freezing point at 100 °C. One year later Frenchman Jean Pierre Cristin proposed to invert the scale. He named it Centigrade.In later years, probably when the lower reference temperature was switch to the Triple Point, the name Celsius was restored.MFMcGraw Ch13c-Temperature-Revised-4/25/10 12Fahrenheit Temperature ScaleIt was in 1724 that Gabriel Fahrenheit, an instrument maker of Däanzig and Amsterdam, used mercury as the thermometric liquid. Fahrenheit described how he calibrated the scale of his mercury thermometer: "placing the thermometer in a mixture of sal ammoniac or sea salt, ice, and water a point on the scale will be found which is denoted as zero. A second point is obtained if the same mixture is used without salt. Denote this position as 30. A third point, designated as 96, is obtained if the thermometer is placed in the mouth so as to acquire the heat of a healthy man." (D. G. Fahrenheit,Phil. Trans. (London) 33, 78, 1724) On this scale, Fahrenheit measured the boiling point of water to be 212. Later he adjusted the freezing point of water to 32 so that the interval between the boiling and freezing points of water could be represented by the more rational number 180. Temperatures measured on this scale are designated as degrees Fahrenheit (° F). http://www.cartage.org.lb/en/themes/sciences/Physics/Thermodynamics/AboutTemperature/Development/Development.htmMFMcGraw Ch13c-Temperature-Revised-4/25/10 13Temperature Scales273.15C459.67 F0 KAbsolute zero0 C32 F273.15 KWater freezes*100 C212 F373.15 KWater boils*Celsius scaleFahrenheit scaleAbsolute or Kelvin scale(*) Values given at 1 atmosphere of pressure.•In general, as the temperature of a substance is lowered the atomic motion and vibrations slow down.•Temperature can be related to molecular energy. Negative temperature values imply erroneous negative energy. •The Kelvin temperature scale avoids this problem.MFMcGraw Ch13c-Temperature-Revised-4/25/10 14The temperature scales are related by: F32CF/ 8.1CF