More Gas Laws FUNDAMENTALS TEMPERATURE TEMPERATURE Temperature is a measure of the average kinetic energy of the molecules of a substance Kinetic Energy = ½ m × v2 • Where m = mass and v = velocity Temperature of a material is related to the velocity of its particles HEAT Heat is energy transferred due to differences in temperature The energy always flows from higher to lower temperature TEMPERATURE SCALES Celsius or Centigrade (0°C): • Based on the boiling and freezing points of water • Designed so that there would be 100 degrees between them Kelvin (K): • Based on absolute zero; the temperature where all molecular motion stops • 0 Kelvin = -273 oCelsius Temperature Conversions K = oC + 273 oC = K -273 STP Standard temperature is 273K or 0 °C Standard pressure (1 atm) Together standard temperature and pressure are abbreviated STP • Standard set of conditions for experimental measurements • Allows comparisons to be made between sets of data when working with gases TEMP SAMPLE CONVERSIONS: TRY THESE: SOLUTIONS: 1. 86 K to oC 1. -187 oC 2. 6.23 oC to K 2. 279.23 K 3. 191 K to oC 3. -82 oC 4. 9.18 oC to K 4. 282.18 oC 5. 894 K to oC 5. 621 oC NOW YOU TRY!! If the sentence uses Celsius, rewrite it using Kelvin, or vice versa. 1. It has to be 0°C or colder before it will snow outside. 0 + 273 = 273 K 2. If your body temperature is 313K, you probably have the flu. 313 - 273 = 40°C 3. I prefer my classroom to be 296K. 296 - 273 = 23°C CHARLES’S LAW Charles’s Law Ø French physicist (1746-1823) Ø First person to fill a balloon with hydrogen gas Ø Made the first solo balloon flight Charles’s Law Ø Charles’s Law states at constant pressure the volume of a fixed amount of gas is directly proportional to its absolute temperature Ø If volume INCREASES, temperature INCREASES Ø If volume DECREASES, temperature DECREASES V1 V2 = T 1 T2 Ø If the temperature is given in Celsius it must first be converted to Kelvin Ex. Problem #1: Charles’s Law Ø A gas sample at 313 K occupies a volume of 2.32 L. If the temperature is raised to 348 K what will the volume be assuming the pressure remains constant? GIVEN: V1 = 2.3 L T1 = 313K V2 = ?? T2 = 348K WORK: Cross Multiply and Divide Ex. Problem #2: Charles’s Law Ø A gas at 348 K occupies a volume of .45L. At what temperature will the volume be .95L? GIVEN: V1 = T1 = V2 = T2 = WORK Cross Multiply and Divide GAY-LUSSAC’S LAW Gay-Lussac’s Law Ø If the number of moles and volume are constant, then pressure is directly proportional to temp (K) Ø If pressure INCREASES, then temperature INCREASES Ø If pressure DECREASES, then temperature DECREASES P1 P2 = T1 T2 Ex. Problem #1: Gay-Lussac’s Law Ø The pressure of a gas in a tank is 3.20 atm at 295 K. If the temperature rises to 333 K what will be the gas pressure in the tank? GIVEN: P1 = 3.20 atm T1 = 295K P2 = ?? T2 = 333K WORK: Cross Multiply and Divide Ex. Problem #2: Gay-Lussac’s Law Ø A gas in a container has a pressure of 85 KPa at a temperature of 303 K. If the pressure is increased to 150 KPa what is the new temperature? GIVEN: WORK: Cross Multiply and Divide
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