Behavior of Gases Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8.
Behavior of Gases 2 Study Guide: Things You Must Know Vocabulary (know the definition and what it means): state of matter Kinetic Molecular Theory (KMT) elastic collision molecular attractions (intermolecular forces) pressure atmospheric pressure Boyle s Law Charles Law Avogardo s Law Ideal Gas Law ( pivnert ) Combined Gas Law ideal gas vs. real gas Dalton s Law of Partial Pressure Diffusion vs. effusion Honors: Graham s Law of Diffusion Learning Objectives: the statements (or assumptions) that make up Kinetic Molecular Theory. how to explain the Gas Laws using Kinetic Molecular Theory. what pressure is at the molecular level. how to interconvert units of pressure (atmospheres, mm Hg, pascals). Kelvin temperature is a measure of average kinetic energy. Kelvin temperature must be used in all Gas Law problems. when to use the Ideal Gas Law and when to use the Combined Gas Law. how to solve problems using the Ideal Gas Law and the Combined Gas Law. what distinguishes an ideal gas from a real gas. under what conditions of temperature and pressure a real gas is most like an ideal gas. How to solve problems with mixtures of gases using Dalton s Law of partial pressures. Honors: how to calculate relative rates of diffusion and effusion using Graham s Law. Key Reference Tables Table A: Standard Temperature and Pressure Table T: Important Formulas and Equations
Behavior of Gases 3 Read Chapter 12. Regents students can skip the section on Graham s Law, pp 352-353. Lab 11: Boyle s Law Lab 11b: Charles Law Regents Tables: Table A: Standard Temperature and Pressure Table T: Important Formulas and Equations Warm-ups and problems will be collected before you take the test. Answer all problems in the space provided. For problems involving an equation, carry out the following steps: 1. Write the equation. 2. Substitute numbers and units. 3. Show the final answer with units. There is no credit without showing work. Kinetic Molecular Theory (KMT) 1. State the main assumptions of KMT. 2. What is the effect of adding gas to a container on the pressure in the container. Explain at the molecular level. 3. What is the effect of increasing the volume of a container on the pressure in the container. Explain at the molecular level. 4. What is STP? 5. Why is Kelvin temperature used in all gas law calculations? Two Variable Gas Laws 6. The pressure on 2.50 L of anesthetic gas changes from 105 kpa to 40.5 kpa. What will be the new volume if the temperature remains constant? 7. Exactly 5.00 L of air at 50 o C is warmed to 100 o C. What is the new volume if the pressure remains constant?
Behavior of Gases 4 8. The pressure in an automobile tire is 198 kpa at 27 o C. At the end of a road trip on a hot day, the pressure in the tire has risen to 225 kpa. What is the temperature of the air in the tire? Ideal Gas Law 9. What is the value of the ideal gas constant? 10. When the temperature of a rigid 685 L container of helium gas is held at 621 K, the pressure in the container is 1.89 x 10 3 kpa. How many moles of helium is in the container? If the gas were CO 2 instead of helium, how many moles would there be in the container? 11. What volume will 12.0 g of oxygen gas occupy at 25 o C and a pressure of 52.7 kpa? 12. A container holds 6.92 g of helium gas at STP. What is the volume of the container? 13. If the human lung has a volume of 3.1 L, how many grams of air at 102 kpa and at normal body temperature of 37 o C will it hold. (Assume the average molar mass of air is 28 g/mol.) Combined Gas Law 14. A gas at 155 kpa and 25 o C occupies a volume of 1.0 L. By changing the volume, the pressure of the gas increases to 605 kpa and the temperature increases to 125 o C. What is the new volume? 15. A 5.00 L air sample at 50 o C has a pressure of 0.78 atm. What will be the new pressure if the temperature is raised to 102 o C and the volume expands to 7.00 L?
Behavior of Gases 5 Mixed-up Combined and Ideal Gas Law Problems! Note: There are two main equations in this unit, the ideal gas law and the combined gas law. If conditions of P, V, or T do not change, use the Ideal Gas Law. If conditions do change, use the Combined Gas Law. 1. Ideal Gas Law (alias pivnert ): PV = nrt. The most error-free way to use this equation is to convert units: pressure (P) to atmospheres volume (V) to liters number of moles (n) to moles temperature (T) to Kelvin and use the gas constant R = 0.0821 L atm/mol K 2. Combined Gas Law: P1V1 = P2V2 T1 T2 This equation can be used with any units of P and V as long as they are the same on both sides. T must be in Kelvin. 16. 11 g of methane (CH 4) is placed in a rigid 820 ml container at 120 o C. What is the pressure in the container? 17. Neon gas is placed in a 31 L tank at 35 o C and a pressure of 750 kpa. What is the new pressure if the temperature is changed to 120 o C? 18. How many moles of propane (C 3H 8) are in a tank if the temperature is 27 o C, the pressure is 450 kpa, and the volume of the tank is 930 L? 19. Honors If the volume of a gas doubles and the Kelvin temperature triples, what happens to the pressure? Dalton Law of Partial Pressures 20. Determine the total pressure of a gas mixture that contains the following partial pressures: P(O 2) = 20.0 kpa, P(N 2) = 46.7 kpa, and P(He) = 26.7 kpa. 21. A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 32.9 kpa. What is P(CO 2) if P(O 2) = 6.6 kpa and P(N 2) = 23.0 kpa?
Behavior of Gases 6 Graham s Law of Diffusion 22. Honors At the same temperature, the rates of diffusion of carbon monoxide and nitrogen at virtually the same. Explain. 23. Honors Which gas diffuses faster, hydrogen or chlorine. How much faster? 24. Honors A certain gas diffuses four time faster than oxygen (O 2). What is the molar mass of the gas? Real vs. Ideal Gases 25. Define ideal gas. 26. Explain, on the molecular scale, why real gases deviate from ideal behavior. 27. Under what conditions of temperature and pressure do real gases behave most like ideal gases. Explain. Review 28. Calculate the molar mass of calcium acetate. 29. How many kilojoules of heat are requires to warm 500 g of water from 22 o C to 72 o C? 30. Write an equation for the reaction of aluminum metal with a solution of copper (II) sulfate. What class of reaction is this? 31. Calculate the molecular formula of a compound with an empirical formula of C 2H 4O and a molar mass of 88 g/mol.