Mastering Gas Stoichiometry and the Ideal Gas Law in Chemical Reactions

1. Gas Stoichiometry Ideal Gas Law Gas Stoichiometry

2. The Ideal Gas Law • Putting It All Together • PV = nRT n = moles P = pressure Temp = must be in Kelvin Volume = must be in Liters Should be able to solve for any R but you won’t have to

3. Solving for R values • Use STP

4. PV = nRT • Straight Ideal Gas law problem: Sprinkled all over the AP => another way to get moles. 2) Problem: Got moles, Do stoich!

5. Sample Problem 1 • For an ideal gas, calculate the pressure of the gas if 0.215 moles occupies 338 mL at 32°C.

6. Sample Problem 2 • Acetic acid reacts with solid sodium carbonate. • 5.00 grams of sodium carbonate is added to 20.0 mL of 1.50 M acetic acid. What volume of CO2 is produced at 0.878 atm and 23°C?

7. Sample Problem 3 • Sodium metal is added to water. • If 43.2 mL of hydrogen gas are produced at 767 torr and 59°C in excess water, how many grams of sodium were reacted?

8. Finding the Molar Mass of a Gas • Should be provided grams of the gas • Use PV = nRT to find the moles • MM = grams moles

9. Manipulation of the Ideal Gas Law #1 PV = nRT n= mass mole mass so……. PV = mass RT mole mass

10. Manipulation of the Ideal Gas Law #2 PV = nRT n= mass mole mass P = (mass R T) (volume x mole mass) or P = (density R T) MM = DRT mole mass P

11. Manipulation of Ideal Gas Law • The density of a gas was measured at 1.50 atm and 27°C and found to be 1.95 g/L. Calculate the molar mass of this gas.

12. Dalton Law of Partial Pressures Key: Ptotal = P1 + P2 + P3 +…. The total pressure = the sum of all the partial pressures

13. Dalton Law of Partial PressuresManipulation Ptotal = P1 + P2 + P3 +…. Ptotal = n1RT + n2RT + n3RT +….. V V V Sum of the moles of gases; who cares what they are

14. Application of Dalton’s Law of Partial Pressures HUGE! Collecting pressure over water Pair Pgas Pwater

15. Collecting pressure over water Pair = Pgas + Pwater Pair Pgas Pwater Pwater is dependent on temperature