Gases and the Kinetic Molecular Chapter 5 Theory Learning Objective Discuss history of gas laws and how they come together to form ideal gas law Perform ideal gas law calculations with and without changing conditions 1 The three states of matter 2 Gas Pressure and its Measurement Pressure force area Atmospheric pressure arises from the force exerted by atmospheric gases on the earth s surface Atmospheric pressure decreases with altitude 3 Common Units of Pressure Unit Normal Atmospheric Pressure at Sea Level and 0 C These are exact quantities in calculations we use as many significant figures as necessary 4 Behavior of Gases The physical behavior of gases is defined by Pressure Temperature Volume Amount Variables are interdependent Relationships described by the gas laws 5 Robert Boyle 1627 1691 Changes in pressure and volume of a gas are inversely proportional 6 Volume is inversely proportional to Pressure or Boyle s law 7 Jacques Charles 1746 1823 Temperature and Volume are proportional or or 8 Charles s law Temperature and volume are proportional 9 Absolute zero 0 K is the temperature at which an ideal gas would have a zero volume Absolute zero is the temperature at which an ideal gas would have a zero volume 10 Pressure is proportional to temperature Amontons Law or or 11 Amadeo Avogadro 1776 1856 Volume is directly proportional to number of moles 1 1 2 2 12 Avogadros Law Volume is proportional to number of moles At fixed temperature and pressure the volume occupied by a gas is directly proportional to the amount of gas Avogadro s Law at fixed temperature and pressure equal volumes of any ideal gas contain equal numbers of particles or moles 13 Standard molar volume at standard temperature and pressure 1mol 1mol 1mol 1 atm 760 torr 1 atm 760 torr 1 atm 760 torr 0 273 15 K 0 273 15 K 0 273 15 K 22 4 L 22 4 dm3 22 4 L 22 4 dm3 22 4 L 22 4 dm3 mass 4 003 g mass 28 02 g mass 32 00 g 0 179 g L 1 25 g L 1 43 g L 14 IDEAL GAS LAW fixed and fixed and fixed and Boyle s law Charles s law Avogadro s law The individual gas laws as special cases of the ideal gas law ideal gas law puts it all together for you KNOW THE IDEAL GAS LAW 15 IDEAL GAS LAW fixed and fixed and fixed and Boyle s law Charles s law Avogadro s law The Universal Gas Constant You need when calculating one quantity from the others You don t need when calculating a change in conditions 16 A sample of has a volume of at and What is the temperature if that sample changes to a volume of pressure is held constant A 182 K B 298 K C 387 K D 489 K E 538 K https etc ch BJpU 17 A sample of propane has at and What is at STP A 25 2 L B 33 6 L C 37 1 L D 40 5 L E 49 4 L https etc ch BJpU 18 At what temperature in will of gas occupy at a pressure of A B C D E https etc ch BJpU 19 A gas occupies a volume of at STP Calculate the temperature in needed to change the volume to and the pressure to A B C D E https etc ch BJpU 20