1. Ideal Gas Law & Gas Stoichiometry Work out each problem in the 3-step format. Gases notes #4 - Ideal Gas Law & Gas Stoichiometry.pptx

2. After this lesson you will be able to: Solve problems involving the gas laws involving chemical reactions Apply stoichiometry principles in addition to gas laws Recognize which equations to apply in different types of problems involving gases

3. QUESTION #1 How many grams of CO 2 are produced from 75 L of CO at 35°C and 96.2 kPa? 2CO + 1O 2  2CO 2

4. Find the moles of CO: n = ? mol V = 75 L P = 96.2 kPa T = 35°C R = 0.08206 L  atm/mol  K Use: PV = nRT n = 2.818023828 mol CO 2CO + 1O 2  2CO 2 ? g 75 L, 35 °C, 96.2 kPa ANSWER #1, part 1 = 0.949654491 atm = 308 K

5. ANSWER #1, part 2 Use stoichiometry: 2CO + 1O 2  2CO 2 2.818023828 mol ? g 2.818023828 mol CO 2 mol CO 2 2 mol CO 44.01 g CO 2 1 mol CO 2 = 120 g CO 2

6. QUESTION #2 How many moles of oxygen will occupy a volume of 2.5 L at 1.2 atm and 25°C?

7. ANSWER #2 n = ? V = 2.5 L P = 1.2 atm T = 25°C R = 0.08206 L  atm/mol  K Use: PV = nRT n = 0.12 mol = 298 K

8. QUESTION #3 What volume will 56.0 grams of nitrogen gas occupy at 96.0 kPa and 21°C?

9. ANSWER #3 V = ? n = 56.0 g P = 96.0 kPa T = 21°C R = 0.08206 L  atm/mol  K Use:PV = nRT V = 50.9 L = 1.998572448 mol = 0.947680157 atm = 294 K

10. QUESTION #4 What volume of NH 3 at STP is produced if 25.0 g of N 2 is reacted with excess H 2 ? 1N 2 + 3H 2  2NH 3

11. ANSWER #4 25.0 g N 2 1 mol N 2 28.02 g N 2 = 40.0 L NH 3 1 N 2 + 3 H 2  2 NH 3 2 mol NH 3 1 mol N 2 22.4 L NH 3 1 mol NH 3 25.0 g? L, STP Use stoichiometry: excess limiter

12. QUESTION #5 What volume of hydrogen is produced from 25.0 g of water at 27°C and 1.16 atm? 2H 2 O  2H 2 + 1O 2

13. ANSWER #5, part 1 25.0 g H 2 O 1 mol H 2 O 18.02 g H 2 O = 1.387347392 mol H 2 2 mol H 2 2 mol H 2 O 2H 2 O  2H 2 + 1O 2 25.0 g ? L, 27  C, 1.16 atm Use stoichiometry:

14. ANSWER #5, part 2 Find the product volume: n = 1.387347392 mol V = ? P = 1.16 atm T = 27°C R = 0.08206 L  atm/mol  K Use: PV = nRT V = 29.4 L 2H 2 O  2H 2 + 1O 2 ? L, 27  C, 1.16 atm (= 1.387347392 mol) 25.0 g = 300 K

15. QUESTION #6 How many atmospheres of pressure will be exerted by 25 g of CO 2 at 25°C and 0.500 L?

16. ANSWER #6 P = ? n = 25 g T = 25°C V = 0.500 L R = 0.08206 L  atm/mol  K Use: PV = nRT P = 28 atm = 0.568057715 mol = 298 K

17. QUESTION #7 How many grams of CaCO 3 are required to produce 45.0 L of CO 2 at 25°C and 2.3 atm? 1CaCO 3 + 2HCl  1CO 2 + 1H 2 O + 1CaCl 2

18. ANSWER #7, part 1 Find the moles of product: n = ? V = 45.0 L P = 2.3 atm T = 25°C R = 0.08206 L  atm/mol  K Use: PV = nRT n = 4.232457181 mol ? g 45.0 L, 25  C, 2.3 atm 1 CaCO 3 + 2 HCl  1 CO 2 + 1 H 2 O + 1 CaCl 2 = 298 K

19. ANSWER #7, part 2 4.232457181 mol CO 2 = 4.2 x 10 2 g CaCO 3 1 CaCO 3 + 2 HCl  1 CO 2 + 1 H 2 O + 1 CaCl 2 1 mol CaCO 3 1 mol CO 2 ? g 45.0 L, 25  C, 1 atm, 4.232457181 mol 100.09 g CaCO 3 1 mol CaCO 3 Use stoichiometry:

20. QUESTION #8 Find the number of grams of CO 2 that exert a pressure of 785 torr at 32.5 L and 32°C.

21. ANSWER #8 n = ? P = 785 torr V = 32.5 L T = 32°C R = 0.08206 L ⋅ atm / mol ⋅ K Use: PV = nRT n = 1.341244869 mol Convert using molar mass: = 59.0 g CO 2 = 1.032894737 atm = 305 K

22. Tips for solving problems with gases: 1.Is there a chemical reaction happening? If yes, then write the balanced equation and use stoichiometry. 2.Are there changing conditions? If yes, then use the Everything Law (convert T to Kelvins). 3.No changing conditions? Use the Ideal Gas Law (convert all units to match R).