Workshop CHE 168
Problem Set #1
1. Bubbles of oxygen gas from photosynthesis form on the leaves of an underwater plant at a depth of 131 ft. If the plant is growing near the coast of New Jersey on a day on which the atmospheric pressure is 729 mmHg, what is the pressure of the oxygen gas in one of the bubbles mentioned above?2. Calculate the number of kilograms of helium needed to inflate a balloon to a volume of 1.00 x 105 L at an atmospheric pressure of 250 mmHg and a temperature of -35 oC.
3. What pressure in atmospheres will be exerted by 11.0 kilomoles of methane (CH4) when stored at 22 oC in a 3.00 x 103 L tank?
4. A balloon has a volume of 1.50 x 103 L of helium at 0.901 atm and 25 oC. At an altitude of 20 km the temperature is -50 oC and the atmospheric pressure is 76.0 mmHg. What is the volume of this balloon at 20 km?
5. How many grams of N2O, nitrous oxide, is contained in 500 mL of the gas at STP?
6. A sample of nitrogen gas has a volume of 32.4 L at 20 oC. The gas is heated to 220 oC at constant pressure. What is the final volume of nitrogen?
7. 0.500 mol of ammonia (NH3) occupies a 1.2 L flask at 150 oC. Calculate the pressure of ammonia.
8. At what temperature will a fixed mass of gas with a volume of 125 L at 15.0 oC and 750 mmHg occupy a volume of 101 L at a pressure of 645 mmHg?
9. If the pressure on a sample of gas (constant number of moles) is tripled and the absolute temperature is quadrupled, by what factor will the volume of the sample change?
10. If the pressure of a sample of gas with a constant number of moles is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sample change?
11. Determine the molar mass of Freon-11 gas if a sample weighing 0.597 g occupies 100 cm3 at 95 oC, and 1000 mmHg.
12. Calculate the density in g/L of CO2 gas at 27 oC and 0.50 atm pressure.
13. A mixture of three gases has a total pressure at 298 K of 1380 mmHg. The mixture is analyzed and is found to contain 1.27 mol CO2, 3.04 mol CO, and 1.50 mol Ar. What is the partial pressure of Ar?
14. A sample of hydrogen gas was collected over water at 21 oC and 685 mmHg. The volume of the container was 7.80 L. Calculate the mass of H2(g) collected. (Vapor pressure of water = 18.6 mmHg at 21 oC.)
15. What mass of KClO3 must be decomposed to produce 126 L of oxygen gas at 133 oC and 0.880 atm?
2 KClO3 (s) ® 2 KCl (s) + 3 O2 (g)
16. How many liters of chlorine gas at 200 oC and 0.500 atm can be produced by the reaction of 12.0 g of MnO2 with HCl as follows?
MnO2 (s) + 4 HCl (aq) ® MnCl2 (aq) + 2 H2O (l) + Cl2 (g)
17. What mass of potassium chlorate, KClO3, must be decomposed to produce 126 L of oxygen gas at 133 oC and 0.880 atm?
2 KClO3 (s) ® 2 KCl (s) + 3 O2 (g)
18. Cyanogen is a compound of carbon and nitrogen. On combustion is excess oxygen, 500 mL of cyanogen gives 500 mL of N2 and 1000 mL of CO2, all measured at the same temperature and pressure. What is the formula of cyanogen?
19. A sample of zinc metal is allowed to react completely with an excess of hydrochloric acid:
Zn (s) + 2 HCl (aq) ® ZnCl2 (aq) + H2 (g)
The hydrogen gas produced is collected over water at 25.0 oC. The volume of the gas is 7.80 L and pressure is 0.980 atm. Calculate the amount of zinc metal in grams consumed in the reaction. (Vapor pressure of water at 25.0 oC = 23.8 mmHg.)
20. A mixture of gases contains 4.46 moles of neon, Ne, 0.74 moles argon, Ar, and 2.15 moles of xenon, Xe. Calculate the partial pressures of the gases if the total pressure is 2.00 atm at a certain pressure.
21. It requires 57.1 seconds for 1.42 L of an unknown gas to effuse through a pinhole, and it takes 83.9 seconds for the same volume of N2 gas to effuse at the same temperature and pressure. What is the molar mass of the unknown gas?
22. List the following gases in order of increasing diffusion rates: PH3, ClO2, Kr, NH3, HI. Calculate the ratio of diffusion rates of fastest to slowest.