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Not so long ago, in a chemistry lab far far away…. May the FORCE/area be with you. Episode I ATTACK OF THE GAS Gas, being of upmost importance to the entire galaxy and your life, is in constant battle due to the ruthless variations of temperature, pressure, and the amount of particles.
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Not so long ago, in a chemistry lab far far away… May the FORCE/area be with you Episode I ATTACK OF THE GAS Gas, being of upmost importance to the entire galaxy and your life, is in constant battle due to the ruthless variations of temperature, pressure, and the amount of particles. It is imperative that you understand properties of gases and how those ruthless variations affect the gases. You will need to make some minor assumptions to conquer this topic. However, there is certainty that you will prevail…
Gas Laws: Gas StoichiometryAt the conclusion of our time together, you should be able to: Use the Ideal Gas Law to solve a gas stoichiometry problem.
Gases and Stoichiometry 2 H2O2 (l) ---> 2 H2O (g) + O2 (g) Decompose 1.1 g of H2O2 in a flask with a volume of 2.50 L. What is the volume of O2 at STP? Bombardier beetle uses decomposition of hydrogen peroxide to defend itself.
Gases and Stoichiometry 2 H2O2 (l) ---> 2 H2O (g) + O2 (g) Decompose 1.1 g of H2O2 in a flask with a volume of 2.50 L. What is the volume of O2 at STP? Solution 1.1 gH2O2 1 mol H2O2 1 mol O2 22.4 L O2 34 g H2O2 2 mol H2O2 1 mol O2 = 0.36 L O2at STP
x 4.00 g He 1 mol He x 1 mol He 22.4 L He Gas Stoichiometry: Practice! How many grams of He are present in 8.0 L of gas at STP? 8.0 L He = 1.4 g He
Gas StoichiometryTrick Page 41:1 If reactants and products are at the same conditions of temperature and pressure, then mole ratios of gases are also volume ratios. 3 H2(g) + N2(g) 2NH3(g) 3 moles H2 + 1 mole N2 2 moles NH3 67.2 litersH2+ 22.4 liter N2 44.8 liters NH3
Gas StoichiometryTrick Example How many liters of ammonia can be produced when 12 liters of hydrogen react with an excess of nitrogen in a closed container at constant temperature? 3 H2(g) + N2(g) 2NH3(g) 12 L H2 2 L NH3 = L NH3 8.00 3 L H2
What if the problem is NOT at STP? • 1. You will need to use PV = nRT
Gas StoichiometryExample Page x:1 How many liters of oxygen gas, at 1.00 atm and 25 oC, can be collected from the complete decomposition of 10.5 grams of potassium chlorate? 2 KClO3(s) 2 KCl(s) + 3 O2(g) 10.5 g KClO3 1 mol KClO3 3 mol O2 122.55 g KClO3 2 mol KClO3 0.13 mol O2
Gas StoichiometryExample Page x:1 How many liters of oxygen gas, at 1.00 atm and 25 oC, can be collected from the complete decomposition of 10.5 grams of potassium chlorate? 2 KClO3(s) 2 KCl(s) + 3 O2(g) (1.0 atm) (V) (0.13 mol) (0.08206 atm*L/mol*K) (298 K) 3.2 L O2
Gas Laws: Gas StoichiometryLet’s see if you can: Use the Ideal Gas Law to solve a gas stoichiometry problem.
Gas Stoichiometry Page x:2 1 P4(s) + 6 H2 (g) 4 PH3(g) 2.51 g P4 1 mol P4 6 mol H2 123.88 g P4 1 mol P4 0.122 mol H2
Gas Stoichiometry Page x:2 1 P4(s) + 6 H2 (g) 4 PH3(g) (0.991 atm) (V) (0.122 mol) (0.08206 atm*L/mol*K) (298 K) 3.0 L H2
Quicklime Example Page x:3 1 CaCO3(s) 1 CaO (s) + 1 CO2(g) 152 g CaCO3 1 mol CaCO3 1 mol CO2 22.4 L CO2 1 mol CaCO3 1 mol CO2 100.09 g = 34.0 L CO2at STP
Zinc will react with hydrochloric acid. What are the 2 products for this reaction? • ZnCl + H • ZnCl + H2 • Zn2Cl + H2 • ZnCl2 + H2 • Not listed
Zinc will react with hydrochloric acid. What kind of reaction is this? • DD • SD • Synthesis • Decomposition • Not listed
Zinc will react with hydrochloric acid. This reaction will form ZnCl2 + H2. What are the 4 coefficients for the balanced chemical equation? • 1,2,1,2 • 2,1,2,1 • 1,1,1,1 • 2,2,1,2 • Not listed
Zinc will react with hydrochloric acid. The hydrogen gas is collected through water at 30.0oC and 782 mm Hg. The vapor pressure of water at 30.0oC is 32.0 mm Hg. What is the partial pressure of H2? • 250 atm • 314 atm • 0.329 atm • 0.987 atm • Not listed
Zinc ( 65.39 g/mole) will react with hydrochloric acid. Determine the grams of zinc that must be reacted to produce this quantity of hydrogen if the volume is 142 mL . (P = 0.987 atm, T = 30.0oC) • 0.112 g • 1.18 g • 628 g • 0.000 628 g • 0.369 g
Gas Laws: Dalton, Density and Gas StoichiometryAt the conclusion of our time together, you should be able to: Explain Dalton’s Law and use it to solve a problem. Use the Ideal Gas Law to solve a gas density problem. Use the Ideal Gas Law to solve a gas stoichiometry problem.
Lower density High density GAS DENSITY 22.4 L of ANY gas AT STP = 1 mole
Gas Density … so at STP…
Density and the Ideal Gas Law Combining the formula for density with the Ideal Gas law, substituting and rearranging algebraically: M = Molar Mass P = Pressure R = Gas Constant T = Temperature in Kelvins
Gas Stoichiometry #4 How many liters of oxygen gas, at 37.0C and 0.930 atmospheres, can be collected from the complete decomposition of 50.0 grams of potassium chlorate? 2 KClO3(s) 2 KCl(s) + 3 O2(g) 50.0 g KClO3 1 mol KClO3 3 mol O2 = “n” mol O2 122.55 g KClO3 2 mol KClO3 = 0.612 mol O2 = 16.7 L
Try this one! How many L of O2 are needed to react 28.0 g NH3 at24°C and 0.950 atm? 4 NH3(g) + 5 O2(g) 4 NO(g) + 6 H2O(g)