Chapter 5 In-Class Problems Chem201A Dr. Baxley
Chapter 5 In-Class Problems: Gases
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1. A 25.0 L oxygen cylinder contains 3.70 moles of O2 at 2660 mmHg. What is the temperature of the
cylinder in °C? [15 °C]
2. An enclosed cylinder with a constant volume of 5.00 L has a pressure of 2.45 atm at 26.0 ºC. At what
Celcius temperature will the pressure equal 3.15 atm? [111 °C]
3. What is the density of argon at STP? [1.8 g/L]
4. A sample of a noble gas has a mass of 2.168 g and a volume of 0.656 L at 726 mmHg and 22 °C. Which
noble gas is it? [Krypton]
5. A vehicle air bag inflates when the chemical reaction below is initiated by a collision sensor. What mass of
NaN3 must be used in order to inflate an air bag to a volume of 67.2 L in Colorado on a day when the
pressure is 0.817 atm and the temperature is 12.5 ºC? [101 g]
2 NaN3(g) → 2 Na(s) + 3 N2(g)
6. Hydrogen gas created by reacting zinc with HCl is collected
over water. If the volume of gas collected is 265 mL at a
temperature of 25.0 °C and a pressure of 752 mmHg, how
many moles of hydrogen gas were produced?
[0.0104 moles]
7. If 0.0560 L of 0.220 M hydrogen peroxide decomposes according to the equation below at 745 mmHg and
15.3 ºC and the oxygen gas that is created is collected over water, what volume of oxygen gas will form?
[151 mL]
2H2O2(aq) → 2H2O(l) + O2(g)
8. Calculate the mass of aluminum metal that must react with nitric acid to produce 78.6 L of hydrogen gas
collected over water at 35.0 °C and 0.951 atm. [50.1 g]
Conceptual Question: What forces allow a vacuum cleaner to collect dust and dirt?