Unit 8 Study Guide The Properties of Gases General Info: The Unit 8 Test will take place on Wednesday25 April. This test will include multiple choice, problems, and “in other words” questions. You will be provided with: o Conversion factors for units of pressure o Values for the universal gas constant, R Objectives: You should be able to: explain gas behavior in terms of kinetic molecular theory (KMT) convert units of pressure solve combined gas law problems (where P, V, and/or T are changing) perform calculations given data from experiments involving collecting gases over water, e.g. calculating molar mass apply Dalton’s Law of Partial Pressures use molar volume (22.4 L/mol) to do stoichiometry at STP solve ideal gas law problems (given 3 of the following 4 variables: P, V, n, T) explain how and why real gases behave differently from ideal gases Practice Problems/Questions 1. What are the five tenets of kinetic molecular theory (KMT)? 2. Using KMT, explain how gas particles exert pressure. Why does an increase in temperature result in an increase in pressure? 3. Which will move more quickly at a given temperature, He or N2? Explain. 4. What is a barometer and how does it work? 5. Convert the following pressures into the requested units: a. 745 mm Hg = ________ atm c. 0.95 atm = ________ kPa b. 450 kPa = ________ torr d. 1200 torr = ________ mm Hg 6. A gas of volume V is placed in an expandable container. Determine the new volume if conditions are changed in each of the following ways: a. The absolute temperature is tripled. b. The pressure is increased by a factor of six. c. The absolute temperature is tripled and the pressure is increased by a factor of six. d. More gas is added until the number of moles is four times its original value. 7. Hydrogen gas is collected over water and the following data are collected: Measurement Patm Temperature Volume of “wet” gas Mass of H2 Honors Chemistry Reading 0.975 atm 28˚C 251 mL 0.0229 g a. What is the partial pressure of the H2 in the collection flask? b. Calculate the molar volume of H2 based on the data from this experiment. c. What is the percent error for the molar volume? Raleigh Charter High School Dr. Genez Unit 8 Study Guide The Properties of Gases 8. You want the pressure inside a bottle to be 75.0 kPa at 23˚C. At what temperature (in ˚C) should you seal the bottle when the pressure is 1.12 atm? 9. A diver’s lungs hold about 20.0 L of air underwater at a pressure of 1.15 atm and 21˚C. Assuming she holds her breath (and her lungs don’t burst) what will be the volume of her lungs at the water’s surface where the pressure is 1.00 atm and the temperature is 30˚C? 10. A soccer ball containing 12.0 L of gas at 23˚C is left outside on a cold winter day. By what percentage will the ball’s volume decrease if the temperature drops to 0˚C? 11. What is the mass of 5.0 L of CO2 at STP? 12. How many liters of ethane (C2H6) gas are required to produce 22.0 g of CO2 at STP? 13. How many liters of ammonia gas can be produced from 50.0 L of hydrogen and 15.0 L of nitrogen at STP? How many liters of the excess reactant are left over? 14. How many moles of chloroform (CHCl3) are required to fill a 253 mL flask at 100˚C and 940 torr? 15. A balloon contains 4.00 mol H2, 2.00 mol O2, and 3.00 mol N2 at STP. a. What is the total volume of the balloon? b. What is the total pressure inside the balloon? c. What is the partial pressure of O2 in the balloon? 16. Ozone (O3) molecules in the stratosphere absorb much of the harmful radiation from the sun. The temperature and pressure of ozone in the stratosphere are 250 K and 1.0x10-3 atm. a. How many moles of ozone are present in 1.0 L of air under these conditions? b. How many ozone molecules are present in 1.0 L of air under these conditions? 17. Under what conditions do gases not exhibit ideal behavior? Honors Chemistry Raleigh Charter High School Dr. Genez