CH 101 1st Edition Lecture 15 Outline of Last Lecture I Molecular Orbital Theory MO Theory A HOMO and LUMO II Bonding MO s III Antibonding MO s IV Nonbonding MO s A Acceptable and Unacceptable MO bonding Outline of Current Lecture I Ideal Gas Law A Boyle s Law B Charles Law C Avogadro s Law D Gay Lussac s Law II Molarity III Finding the Pressure of a Gas in a Manometer Current Lecture Ideal Gas Law PV nRT I The Ideal Gas Law is an equation that relates different characteristics of a substance based on their correlation These correlations are between pressure P volume V temperature T Amount of moles n and the Ideal Gas Law constant 0 0821 R Ex What is the pressure inside a 7 20L container filled with 13 grams of CO 2 at 35o C This equation requires some conversions before plugging in the numbers into the ideal gas law Convert 13g CO2 moles CO2 13g CO2 1 mol 44 01 g CO2 0 295 mol CO2 n 0 295 mol Convert 35o C Kelvin 35 273 308 K T 308 K Plug into PV nRT P 7 2 0 295 0 0821 308 P 1 03 atm A Boyle s Law o Boyle s law states that pressure and volume are inversely related PV PV B Charles Law o Charles law states that volume and temperature are directly proportional V T V T C Avogadro s Law o Avogadro s law states that volume and the number of moles is directly related which is common sense V n V n This law also tells us that 22 4 Liters I mole D Gay Lussac s Law o This law states that pressure and temperature are directly related P T P T II Molarity III Molarity can be found by using the equation Moles Liters or n V Molarity and molar concentration are the same thing Finding the Pressure of a Gas in a Manometer A manometer is a type of beaker that can hold a gas and measure the pressure When given a picture of a manometer if the gas has a higher pressure than the atmosphere if the gas is pushing down the mercury more than the atmosphere the equation is Pressure of the atmosphere the change in height Pressure of gas atm If the pressure of the gas is less than the pressure of the atmosphere the equation is Pressure of the atmosphere the change in height Pressure of gas atm Ex The pressure of the gas would be found by taking 766 mm Hg 250 mm 784 mm Hg To convert this to atm just divide by 760 mm Hg atm because 1atm 760 mm Hg 784 mm Hg 760 mm Hg atm 1 03 atm