Chapter 14 – Gases
Gas Laws of Boyles', Charles' and Gay-Lussac: Read pages 418-427
1. What are the FIVE assumptions (they are bullet pointed in the text) of the Kinetic Theory of Gases
2. Which of the following factors does NOT affect the properties of a gas
a. pressure b. volume c. number of particles d. mass of particle e. temperature
3. What is Boyle's law and write its mathematical formula
4. What is held constant in a Boyle's law problem (circle TWO answers)
a. pressure b. volume c. number of gas particles d. temperature
5. As far as Boyle's law is concerned, if Pressure goes up, Volume goes __________
6. Do practice problem #1 p. 422
7. Do practice problem #2 p. 422
8. Do practice problem #5 p. 422 (Notice, you will need to convert one of the pressures. It doesn't matter which one, but they both
must be in the same units - either atm or kPa - in order to solve the problem)
9. What is Charles' law and write its mathematical formula
10. What is held constant in a Charles' law problem (circle TWO answers)
a. pressure b. volume c. number of gas particles d. temperature
11. As far as Charles' law is concerned, if Temperature goes up, Volume goes __________
12. What would the volume of a gas be if its temperature dipped to -273oC?
13. What would the molecular motion of a gas be at a temperature of -273oC?
14. What is the temperature, in Kelvins, of -273oC? What is the name of this temperature?
15. If a gas had a temperature of 55oC, how many Kelvins is this?
16. If a gas had a temperature of 300 K, how many oC is this?
17. Do Practice Problem #6 p. 425 (you must first convert Celsius to Kelvin!)
18. Do practice Problem #7 p. 425 (you must first convert Celsius to Kelvin!)
19. What is Gay-Lussac's Law and write its mathematical formula
20. What is held constant in a Gay-Lussac's law problem (circle TWO answers)
a. pressure b. volume c. number of gas particles d. temperature
21. As far as Gay-Lussac's law is concerned, as Pressure goes up, Temperature ________
22. Do practice problem #9 p. 427 (again, Celsius must be first converted to Kelvin)
Questions #23-27 are related: They deal with putting a balloon and a closed Erlenmeyer Flask into a freezer and describing
what happens to the air inside of them.
23. If you were to put a balloon in the freezer, which law describes what happens to the balloon:
a. Boyles'
b. Charles' c. Gay-Lussac's
24. If you were to put a glass Erlenmeyer flask (with a solid rubber stopper in its opening) in the freezer, which law describes what
happens to the gas in the flask?
a. Boyles'
b. Charles' c. Gay-Lussac's
25. Does the gas in the freezing Erlenmeyer flask all congregate in the center of the flask? Or does it spread out evenly throughout
the flask? Explain.
26. Why does the gas in the frozen balloon come together but in the Erlenmeyer flask, it does not?
27. Could the gas in the Erlenmeyer flask ever get together? And if so, what phase of matter would it be in and how could this be
made to happen?
Combined Gas law and Avogadro's Principle - Read p. 428-433
28. What is the Combined Gas Law? Write the formula
29. What one thing must be held constant when using the Combined Gas law (choose ONE)
a. Temperature b. pressure
c. volume d. number of particles of gas e. love
30. Do practice problem #19 p. 430 (remember, temps must be in Kelvin. All Pressures (and Volumes) must be in the same units - it
doesn't matter which units of pressure (or volume), but they must be the same!
31. Do practice problem #20 p. 430
32. What is Avogadro's Principle?
33. Let's say you have a sample of gas with a pressure of 3 atm, a volume of 4 L and a temperature of 80 oC. Which kind of gas would
have more particles under these conditions
a. Ar
b. Kr c. O2
d. He e. They're all the same, that's Avogadro's Principle you dummy!
34. If you have a gas at Standard Temperature and Pressure (STP), what is the value for that gas'
Temperature measured in: ________oC
__________Kelvins
Pressure measured in: _______atm
_________kPa
_________mm Hg
35. If you have a gas at STP, ONE MOLE of ANY gas would fit into what size volume?
36. Why doesn't the mass of a gas matter when solving these problems?
37. Do Practice problem #24 p. 432
38. Do Practice problem #25 p. 432
39. Do practice problem #29 p. 433 (look at example problem 14-6 p. 432 for help. Notice you will need to convert your answer from
moles into grams!)
40. Do practice problem #30 p. 433
41. Why are weather balloons not completely inflated?
The Ideal Gas Law: Read p. 434-439
42. Write the formula for the Ideal Gas Law
43. Look at table 14-1 p. 435 and write the R values for the following conditions
If the pressure is measured in atm ________
If the pressure is measured in kPa ________
If the pressure is measured in mmHg ________
44. Regardless of what the pressure is measured in, when you are solving for Ideal Gas Law problems, what units should be used for
Temperature ________
Volume _________ n ___________
45. What happens to a gas when the temperature gets so low that its intermolecular attractive forces are strong enough to bond them
together?
46. Why do you think it is impossible to have an ideal gas at very low temperatures (such as near absolute zero)?
47. Which formula allows you to solve for the number of gas particles (n)?
a. Combined gas law
b. Ideal gas law
48. Do Practice Problem #41 p. 437 (remember, Temperature must be in Kelvins. Also, the units for pressure will determine which
value of R you will use)
49. Do Practice problem #42 p. 437
50. Do Practice problem #43 p. 437
Gas Stoichiometry - Read p. 440-443
51. True or False: Chemical equations are balanced in units of moles, but since at a given temperature and pressure, the mass of a gas
DOESN'T MATTER, it is safe to assume that a chemical equation's gases are also balanced in units of Volume. (Hint: The answer is
TRUE!)
52. Look at the equation on p. 440 at the top. If you have 2 MOLES of C 4H10, how many MOLES of CO2 would you produce?
53. Look at the equation on p. 440 at the top. If you have 2 LITERS of C 4H10, how many LITERS of CO2 would you produce? (hint:
Look at #49)
54. Do Practice Problem #57 p. 441 (remember, you don't have to convert Liters into Moles because the equation is balanced in
BOTH liters and moles!)
55. Do Practice Problem #58 p. 441 (remember how to balance combustion reactions?)
Stoichiometry and Gas Laws and limiting reagents:
DO THIS ON A SEPARATE SHEET OF PAPER - Show your work!
56. 5.00 g of solid aluminum reacts with 87.6g of Hydrochloric acid. (this is a FABULOUS question to prepare you for the quiz!)
a. Write the chemical equation for this reaction
b. How many moles of HCl do you have? (answer: 2.4 moles)
c. How many moles of Al do you have? (answer: 0.185 moles)
d. Which one is the limiting reagent? (answer: Al)
e. How many MOLES of your excess reagent (which is HCl) will you have left over? (answer: 1.85)
f. How many GRAMS of your excess reagent (which is HCl) will you have left over? (ans: 67.5 g)
g. What is the maximum number of moles of H2 gas that can be produced? (answer: 0.2775 moles)
h. At STP, what volume would this H 2 gas occupy? (answer: 6.22 L)
i. At 120 Kpa and 30oC, what volume would this H2 gas occupy? (answer: 5.83L)
57. 3.00 L of Chlorine gas react with 25.0 g of NaBr in the following reaction.
2NaBr (aq) + Cl2 (g) ------ 2NaCl (aq) + Br2 (g)
a. Which reactant is the limiting reactant? (answer: NaBr is limiting)
b. How many moles of Br2 gas will be formed (maximum)? (answer: 0.121 moles)
c. At STP, how much volume will the Br2 gas occupy? (answer: 2.71 L)
58. 15.0 L of Hydrogen gas is combined with 10.0 grams of Oxygen gas to form dihydrogen monoxide.
Assume this reaction is occurring at STP.
a.
b.
c.
d.
e.
How many moles of Hydrogen gas do you have? (answer: 0.669 mol)
How many moles of Oxygen gas do you have? (answer: 0.313 mol)
Which is the limiting reagent: Hydrogen or Oxygen? (answer: Oxygen)
How many moles of water can be produced (maximum)? (answer: 0.625 moles of water)
How many grams of water can be produced (convert moles produced into grams): (answer: 11.25 g)