Gas

Stoichiometry!

Volume-Volume Coefficients give volume ratios of

GASES in a balanced chemical equation

For example: 2H2 + O2 2H2O means 2 volumes of H2 combine with 1 volume of O2

Sample Problem 11-7 C3H8 + 5O2 3CO2 + 4H2O What is the volume oxygen required

to completely combust 0.350 L of propane?

0.350 L x 5 L O2 = 1.75 L O21 L C3H8

Sample Problem 11-7 Contd.What will be the volume of CO2 produced?

0.350 L C3H8 x 3 L CO2 = 1.05 L CO2 1 L C3H8

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-versaUse IDEAL GAS LAWKeep track of units and what you’re trying to find!

Sample Problem 11-8

CaCO3 CaO + CO2How many grams of calcium carbonate must be decomposed to produce 5.00 L of carbon dioxide gas at STP?

n=PV/RTn= (1 atmo)(5.00 L)(0.08205784 Latmo/moleK)(273 K)

Sample Problem 11-8 Contdn=0.2231966 moles CO20.2231966 mole CO2 x 1 mole CaCO3 = 1 mole CO2

0.2231966 mole CaCO30.2231966 mole CaCO3 x 100.0872 g =1 mole

22.339118 g = 22.3 g CaCO3

Sample Problem 11-9WO3 + 3H2 W + 3H2OHow many liters of hydrogen gas at 35oC and 0.980 atmo are needed to react completely with 875 g tungsten oxide?

875 g WO3 x1 mole WO3= 3.7741839mole 231.8382 g

Sample problem 11-9 Contd 3.7741839 mole x 3 mole H2 =

11.322552 1 mole WO3 mole H2

Then use PV=nRT V=nRT/P V=(11.322552mole)(0.08205784Latmo/

moleK(308.15K) (0.980 atmo) V=292.14622 L H2 = 292 L H2

Sie sind dran! Worksheet 11-3

Now you try it!Do practice problems 1-2 p 348, practice problems 1-2 p 349 and practice problems 1-2 p 350!

Stoichiometry is fun!