Gas Stoichiometry!

Volume-Volume  Coefficients give volume ratios of GASES in a balanced chemical equation  For example: 2H 2 + O 2  2H 2 O means 2 volumes of H 2 combine with 1 volume of O 2

Sample Problem 11-7  C 3 H 8 + 5O 2  3CO 2 + 4H 2 O  What is the volume oxygen required to completely combust L of propane?  L x 5 L O 2 = 1.75 L O 2 1 L C 3 H 8

Sample Problem 11-7 Contd.  What will be the volume of CO 2 produced?  L C 3 H 8 x 3 L CO 2 = 1.05 L CO 2 1 L C 3 H 8

Eeeek! Another problem!  Xenon gas reacts with fluorine gas to produce xenon hexafluoride. If a researcher needs 3.14 L of xenon hexafluoride, what volumes of xenon and fluorine gases are required?

Volume-Mass and Vice-versa  Use IDEAL GAS LAW  Keep track of units and what you’re trying to find!

Sample Problem 11-8  CaCO 3  CaO + CO 2  How many grams of calcium carbonate must be decomposed to produce 5.00 L of carbon dioxide gas at STP?  n=PV/RT  n=(1 atmo)(5.00 L) ( Latmo/moleK)(273 K)

Sample Problem 11-8 Contd  n= moles CO 2  mole CO 2 x 1 mole CaCO 3 = 1 mole CO 2  mole CaCO 3  mole CaCO 3 x g = 1 mole g = 22.3 g CaCO 3

Sample Problem 11-9  WO 3 + 3H 2  W + 3H 2 O  How many liters of hydrogen gas at 35 o C and atmo are needed to react completely with 875 g tungsten oxide?  875 g WO 3 x1 mole WO 3 = mole g

Sample problem 11-9 Contd  mole x 3 mole H 2 = mole WO 3 mole H 2  Then use PV=nRT  V=nRT/P  V=( mole)( Latmo/moleK(308.15K) (0.980 atmo)  V= L H 2 = 292 L H 2

Sie sind dran!  Worksheet 11-3

Now you try it! DDo practice problems 1-2 p 348, practice problems 1-2 p 349 and practice problems 1-2 p 350! SStoichiometry is fun!