1
Gas Laws
1) A cylindrical gas chamber has a piston at one end that can be used to compress or expand the gas. If the gas is initially at 664 torr when the volume is 3.19 L, what will be the volume if the pressure is reduced to 529 torr?
2) Calculate the gas volume in the system described above if the gas begins at 7.26 L and 1.22 atm. and the pressure is increased to 2.46 atm.
3) Air in a steel cylinder is heated from 19 ºC to 42 ºC. If the initial pressure was 4.26 atm, what is the final pressure?
4) A hydrogen cylinder holds gas at 3.67 atm in a laboratory where the temperature is 25 ºC. To what will the pressure change when it is placed in a storeroom where the temperature drops to 7 ºC?
5) Hydrogen remains a gas at very low temperatures. It does not condense to a liquid until the temperature is –253 ºC, and it freezes shortly thereafter at –259 ºC. What are the equivalent absolute temperatures?
6) Sodium chloride melts at 801 ºC. Express this temperature in kelvins.
7) 1.20 L of a gas are heated from 15 ºC to 40 ºC at constant pressure. What will the volume at the higher temperature be?
8) A variable-volume container holds 24.3 L of gas at 55 ºC. If pressure remains constant, what will the volume be if the temperature falls to 15 ºC?
9) A gas occupies 3.40 L at 65 ºC and 686 torr. What volume will it occupy if it is cooled to room temperature, 21 ºC, and compressed to 805 torr?
10) The gas in a 0.717 L cylinder of a diesel engine exerts a pressure of 744 torr at 27 ºC. The piston suddenly compresses the gas to 48.6 atm and the temperature rises to 547 ºC. What is the final volume of the gas?
11) An industrial process yields 8.42 L of NO at 35 ºC and 725 torr. What would this volume be if adjusted to STP?
12) If one cubic foot – 28.4 L – of air at common room conditions of 23 ºC and 739 torr were adjusted to STP, what would the volume become?
13) The pressure gauge reads 125 psi (pounds per square inch) on a 0.140 m3 compressed air tank when the gas is at 33 ºC. To what volume will the contents of the tank expand if they are released to an atmospheric pressure of 751 torr and the temperature is 13 ºC? [14.69 psi = 760 torr]
14) A pressure of 850 torr is exerted by 28.6 g of sulfur dioxide at a temperature of 40 ºC. Calculate the volume of the vessel holding the gas.
15) 17.2 atm is the pressure caused by 6.04 mol of nitrogen monoxide at a temperature of 18 ºC. What is the volume of the gas in liters?
16) At what Celsius temperature will argon have a density of 10.3 g/L and a pressure of 6.43 atm?
17) At what temperature will 0.810 mol of molecular chlorine in a 15.7 L vessel exert a pressure of 756 torr?
18) How many grams of molecular nitrogen will be in a 1.50 L flask at STP?
19) Calculate the mass of 434 L of molecular chlorine, measured at STP.
20) If the density of an unknown gas at STP is 1.63 g/L, what is the molar mass of the gas?
21) The STP density of an unidentified gas is 2.32 g/L. Calculate the molar mass of the gas.
22) The density of an unknown gas at 20 ºC and 749 torr is 1.31 g/L. Estimate the molar mass of the gas.
23) What is the density of neon at 40 ºC and 1.23 atm?
24) Carbon dioxide is released when cream of tartar reacts with baking powder. KHC4H4O6 (s) + NaHCO3 (s)→ NaKC4H4O6 (s) + H2O (g) + CO2 (g). If 8.55 g of NaHCO3 react, what volume of CO2 will be released at 0.949 atm in an oven that is at 325 ºC?
25) One source of sulfur dioxide used in making sulfuric acid comes from sulfide ores by the reaction 4FeS2 (s) + 11 O2 (g) → 2Fe2O3 (s) + 8SO2 (g). Calculate the grams of FeS2 that must react in order to produce 423 L of SO2 measured at 1.48 atm and 384 ºC.
26) Dolomite (CaCO3 · MgCO3) is used in the manufacture of refractory brick for lining very high temperature furnaces. It is processed through a rotary kiln in which carbon dioxide is driven off in the reaction: CaCO3 · MgCO3 → CaO · MgO+ 2CO2. For each kilogram of dolomite processed, how many liters of carbon dioxide escape into the atmosphere at 225 ºC and 825 torr?
27) The reaction chamber in a modified Haber Process for making ammonia by direct combination of its elements is operated at 550 ºC and 250 atm. How many grams of ammonia will be produced by the reaction of 97.0 L of molecular nitrogen if introduced at the temperature and pressure of the chamber?
28) Nitrogen dioxide is used in the chamber process for manufacturing sulfuric acid. It is made by direct reaction of oxygen with nitric oxide: 2 NO (g) + O2 (g) → 2NO2 (g). How many liters of nitrogen dioxide will be produced by the reaction of 155 L of oxygen, both gases being measured at atmospheric conditions, 24 ºC and 752 torr?
29) One of the methods for making sodium sulfate safely, used largely in the production of kraft paper for grocery bags, involves passing air and sulfur dioxide from a furnace over lumps of salt. The equation is 4 NaCl + 2 SO2 + 2 H2O + O2 → 2 Na2SO4 + 4 HCl. (Note the hydrochloric acid, an important by-product of the process.) If 2215 cubic feet of oxygen at 400 ºC and 835 torr react in a given period of time, how many cubic feet of sulfur dioxide react if measured at the same conditions?