Chemistry X - Chapters 13-14 Assignment Sheet Day Fri. 11-4 Lecture Topics/Labs Kinetic molecular theory Intermolecular forces Properties of solids/liquids/gases Molar volume of solids/liquids/gases Demos – diffusion in hot/cold water Alcohol/water Reading and Homework Assignments Read: pg. 385-390; 396-399; 419-420 Skim: pg. 393-396; 399-403 Mon. 11-7 Phase changes Experiment #3: Warming/Cooling of a Solid Read: pg. 404-408 Hwk: Problem Set 1 #1-8only (will grade tomorrow) Tues. 11-8 Collect lab; Correct PS 1; Quiz Pressure/Barometer/ Manometers Gas laws – qualitative discussion Boyle’s Law Lab Hwk: Complete Expt. #3 Complete all of Problem Set 1 (attached) Wed. 11-9 Notes - Boyle’s and Charles Charles’ Law Lab w/notes Demos - Balloon in water Pop Can Boiling w/ice (IMF & gas laws) Marshmallow in syringe Read: pg. 423-425 Hwk: Complete Boyle’s Law Lab Mon. 11-14 Collect PS 2; Quiz (Boyle’s Law Lab and PS 2) Gaw laws – Gay-Lussac, Avogadro, combined Read: pg. 426-429 Hwk: Problem Set 2 Tues. 11-15 Correct PS 3; Quiz Read: pg. 430-433 STP & Room conditions Hwk: Problem Set 3 Density/molar mass calculations Introduce Burning Down the House (Will be due two days after this unit test.) Wed. 11-16 Correct PS 4; Quiz Dalton’s Law of Partial Pressure Collection over water Read: pg. 391-392 Hwk: Problem Set 4 Thurs. 11-17 Correct PS 5; Quiz Molar Volume of H2 Lab Hwk: Problem Set 5 Fri. 11-18 Collect Lab; Quiz Ideal Gas Law Density/ molar mass of gases revisited Gas Stoichiometry Read: pg. 434-443 Hwk: Complete Molar Volume of H2 Lab Mon. 11-21 Correct PS 6; Quiz Hwk: Problem Set 6 Tues 11-22 TEST: Ch. 13-14 (46 mult. choice, 8 pt. free response) • How can you use kinetic molecular theory to distinguish between the properties of solids, liquids and gases? • How can you use kinetic molecular theory to explain gas laws? • How can you calculate pressure, volume, moles or temperature of a gas sample? • How can you use pressure, volume, moles or temperature to determine the density or molar mass of a gas? • How can you use mole ratios to determine amounts of gaseous reactants needed or gaseous products formed? • How can you calculate the partial pressure of a gas in a mixture? • How can you describe what occurs during a phase change in terms of intermolecular forces and energy? Chapter 13-14 Objectives Problem Set 1 1) Students will be able to describe gases in terms of rapidly moving molecules. 2) Students will be able to explain why gases have the physical properties they do in terms of intermolecular forces and the kinetic molecular theory. 3) Students will be able to explain the five assumptions of the kinetic molecular theory. 4) Students will be able to describe the difference between inter- and intra-molecular forces. 5) Students will be able to describe how differences in intermolecular forces lead to different properties of solids, liquids, gases. 6) Students will be able to describe the difference between potential and kinetic energy changes. 7) Students will be able to describe the changes that take place in a phase change and whether these changes absorb or release energy and whether these changes are kinetic or potential energy changes. 8) Students will be able to describe why/when a substance will boil and what factors affect the temperature at which it boils (i.e. strength of intermolecular forces and value of air pressure). Expt. #3- Warming/cooling behavior 1) Students will be able to describe the difference between inter- and intra-molecular forces. 2) Students will be able to describe the difference between potential and kinetic energy changes. 3) Students will be able to describe the changes that take place in a melting and freezing and whether these changes absorb or release energy and whether these changes are kinetic or potential energy changes. 4) Students will be able to describe how the shape of a warming/cooling curve would be affected by various factors (e.g. amount of substance, strength of intermolecular forces). Boyle’s Law Lab (Expt. #4) 1) Students will be able to explain qualitatively and quantitatively how the pressure and volume are related one another. 2) Students will be able to compare/contract the shapes of the following graphs – Pressure due to books vs. volume of gas sample; pressure due to books vs. the reciprocal of volume; total pressure vs. the reciprocal of volume. 3) Students will be able to use a graph of total pressure vs. the reciprocal of volume to determine the value of air pressure (in books). Problem Set 2 1) Students will be able to read barometers and open/closed-end manometers. 2) Students will recognize various pressure units (mmHg, atm, torr, Pa, kPa, psi(lb/in2) and be able to convert between them. (Students must know 1 atm = 760.0 mmHg but will be given other equivalents when needed.) 3) Students will understand what is meant by an absolute scale. 4) Students will be able to explain the significance of absolute zero. 5 ) Students will be able to convert between Celsius and Kelvin temperatures. 6) Students will know Boyle’s Law and Charles’ Law and be able to apply them to various initial/final gas problems. Problem Set 3 1) Students will be able to explain qualitatively how the pressure, volume, temperature, and number of moles of a gas affect one another. 2) Students will be able to determine the dependent and independent variable when comparing any two of the following variables - P,V,T,n. 3) Students will understand what is meant by an absolute scale. 4) Students will be able to explain the significance of absolute zero. 5 ) Students will be able to convert between Celsius and Kelvin temperatures. 6) Students will know Boyle’s Law, Charles’ Law, Gay-Lussac’s Law, and the combined gas law and be able to apply them to various initial/final gas problems. Problem Set 4 1) Students will be able to calculate volumes of gas samples at STP or room conditions and know what is meant by these conditions. 2) Students will be able to calculate the molar mass or density of a gas at STP or “room” conditions. Problem Set 5 1) Students will be able to explain why Dalton’s Law of Partial Pressures is true in terms of the kinetic molecular theory. 2) Students will be able to calculate the partial pressure of gases in a mixture if given either the mass, number of moles, or % molecular composition of each gas. 3) Students will know that water vapor is also present when any gas is collected by water displacement. 4) Students will be able to calculate the partial pressure of a gas collected by water displacement if given a table with water vapor pressures at various temperatures. Molar Volume of H2 Lab (Expt. #10) 1) Students will be able to determine the partial pressure of a gas collected over water. 2) Students will be able to use mole ratios to determine the moles of gas produced in a reaction if the moles of limiting reactant are known. 3) Students will be able to calculate the molar volume of a gas collected by water displacement given the mass of reactant, room temperature, room pressure, vapor pressure of water, volume of gas produced. 4) Students will be able to determine how various lab errors would affect their calculated results. 5) Students will be able to calculate % error. Problem Set 6 1) Students will be able to use the ideal gas law to derive the other gas laws (Boyle’s, Charles’, Gay-Lussac’s, and the combined gas law). 2) Students will be able to use the ideal gas law and known values of P,n,T, V of a gas at STP to calculate the value and units of the ideal gas constant, R. 3) Students will be able to use the ideal gas law to calculate the P,T,n, or V of a gas if given three of the variable. 4) Students will be able to calculate the molar mass or density of a gas at any conditions. 5) Students will be able to use the ideal gas law to complete stoichiometry problems that are not at STP or room conditions. Supplements Chapters 13-14 Problem Set 1 1. Use the Kinetic Molecular Theory to explain the expansion and contraction of gases. 2. Define the term “elastic collision.” 3. The volume occupied by one mole of N2 molecules in the liquid and solid states is about 31 4 ml. The volume occupied by one mole of gaseous N2 molecules is about 22,400 mL. (a) On the basis of these numbers, can we say that the actual volume of the molecules is not significant compared to the total volume of the gas? Explain. (b) How much bigger is the volume occupied by the gas than is the volume occupied by the liquid and solid? What meaning can be attached to this number in terms of a kinetic-molecular model? 4. Describe the liquid state according to the kinetic-molecular theory. (How are they packed and how do they move?) 5. Describe the solid state according to the kinetic molecular theory. (How are they packed and how do they move?) 6. How does the kinetic molecular theory explain the following properties of liquids? (a) relatively high density (b) ability to diffuse (c) their ability to evaporate 7. How does the kinetic molecular theory explain the following properties of solids? (a) definite volume (b) relatively high density of solids (c) extremely low rate of diffusion 8. In the previous two problems, a property of liquids and solids was their relatively high density. Why is the word relatively used? 9. What is evaporation? What is vaporization? What is the difference between vaporization and evaporation? 10. (a)When liquid is vaporized, is that a change in kinetic or potential energy? (b) Explain. 11. Boiling point is not directly related to the molecular weight of the substance. What property is the boiling point related to? 12. Diamond has very strong bonds between carbon atoms. (a) Would you expect diamond to have a high or a low vapor pressure? Explain. (b) Would diamond have a high or low melting point? (Explain in terms of intermolecular forces and how they relate to melting and boiling point.) 13. How does the kinetic theory explain the cooling effect of evaporation? (Hint: Why does your arm feel cool when it’s wet?) 14. (a) What takes more energy – melting or vaporizing a pure substance? (b) Use the kinetic molecule theory to explain your answer? (Hint: What changes in molecular positions are involved in each case?) 15. Atmospheric pressure falls about 25 mm Hg for every 300 m above sea level. How would be the boiling temperature of water near the top of Pike’s Peak, which has an altitude of about 4,300 m (over 14,00 ft) compare to the boiling point of water in this science room? (Is it higher or lower than in the science room?) 16. (a) Explain why food cooks more rapidly in a pressure cooker than in an open pan. (b) Why is a pressure cooker more effective in sterilizing surgical instruments than is boiling water in an unpressurized container. 17. Liquid A has stronger intermolecular forces than Liquid B. (a) Will Liquid A have a higher or lower equilibrium vapor pressure? (b) Will Liquid A have a higher or lower boiling point than liquid B? 18. If 35.0 grams of lithium reacts with excess bromine liquid, how many grams of lithium bromide will be produced? Problem Set 2 1. At sea level, the barometer reads 760 mm Hg (760 torr). What reading might you expect (a) on top of one of the peaks in the Sierra-Nevada mountains? (b) at Furnace Creek, which is below sea level in Death Valley, California? General qualitative estimates are acceptable for both answers. (higher/lower than 760) 2. Explain in terms of a kinetic-molecular model why a metal can collapses when air is pumped out of it with a vacuum pump. 3. A man weighing 60 kg steps into powdery snow and sinks to his waist. The area of each of the man's feet is about 250 cm2. He puts on a pair of skis, each of which has an area of about 1,800 cm2. What pressure, expressed in kg/cm2, does each of the man's feet exert on the snow? (b) What pressure, again in kg/cm 2, is exerted on the bottom of each ski? (c) Why can he walk on top of the snow wearing skis without sinking up to his waist? Assume in each case that the man puts all of his weight on one foot as the pressure is measured. 4. If the mercury level in the open arm of a manometer is 100 mm higher than the mercury surface in the other arm, is the gas pressure higher or lower than atmospheric pressure? 5. Give the pressure for each example shown in Figure 1, which is on the last page of this handout. Assume that all devices are in the same room. 6. Convert each of the following: a. 1 atm = ________ mmHg = _______ torr = ___________ Pa = _________ kPa b. 735 mmHg = ________ atm c. 720. mmHg = _______ kPa 7. Make the temperature conversions indicated here: (a) 100. C to Kelvin (b) 325 K to C (c) -259C to K (d) -117 C to K (e) 298 K to C (f) 78 K to C 8. A gas sample occupies 2.50 L and exerts 630. mmHg. At what volume will it exert 600. mmHg? 9. A gas occupies 0.400 Liters and exerts a pressure of 0.900 atm. What must its volume become in order for the pressure to be 1.80 atm? 10. a. Describe a very simple experiment that would show qualitatively what happens to the volume of a fixed quantity of gas at room temperature when the pressure is increased. b. Describe a somewhat more complicated experiment to determine quantitatively how volume changes at the pressure is increased. c. What two variables were held constant in this study? 11. A lab was completed in which bricks were placed on a syringe filled with oxygen. (Similar to the lab you performed in class where books were placed on a syringe filled with air). At a total pressure of 5.5 bricks the value of 1/V is 0.070. a. What will the pressure beat a value of 1/V = 0.140? b. At 1/V = 0.110? c. At 1/V = 0.020? 12. 13. A 4.00 mol gas sample occupies 350. L at 22°C. What volume will it occupy at 35°C? You have one mole of gas at 0°C and 1.00 atmosphere. The pressure is increased to 2.00 atmospheres. A. What will the new volume be? B. How has the number of particles per unit volume changed as a result of the pressure increase? 14. A sample of gas occupies 50. L at 22°C. What volume will it occupy at 11°C? 15. If 25.0 grams of zinc metal react in a solution of hydrochloric acid at STP, how many liters of hydrogen gas will be produced? Problem Set 3 1. Why does a blowout of an automobile tire occur most frequently when the tire is moving over asphalt roads in the middle of the summer? 2. A gas samples exerts 2.12 atm at 40°C. a. What pressure would it exert at 80°C? b. At what temperature would the pressure of this gas sample double? 3. A sample of gas occupies 1.25 L at 700. mmHg and 20° C. What pressure would it exert at 50° C? 4. A gas sample occupies 5.00 L at 730. mmHg and 20°C. What pressure would it exert if the volume is doubled and the absolute temperature tripled? 5. A 2.0 mol gas sample occupies 4.5 L. The number of gas moles is increased to 3.5 moles. What’s the new volume? 6. What will happen to the pressure exerted by a gas if the volume is doubled, absolute temperature is tripled and the number of moles is halved? (multiple choice) a. halved b. x ¾ c. doubled d tripled e. six times 7. If a gas has a volume of 600.0 mL at a pressure of 2.00 atmospheres, what will the volume be at 4.00 atmospheres? The amount of gas and the temperature are constant. 8. Assuming constant temperature and volume for a container, what will be the effect on pressure if the number of molecules in the container is doubled? 9. A 0.500 mol gas sample occupies 2.5 L. The number of gas moles is increased to 0.750 moles. What’s the new volume? 10. A 6.0 L sample of nitrogen gas at 1.90 atm and 25.0 oC is allowed to expand to 8.0 L at 45.0oC. What is the new pressure of the gas? 11. At what pressure will a gas experience a doubling of temperature and volume if initially, the gas was at 20.0 oC, 10.0 L and 3.25 atm? 12. A sample of gas under 2.00 atm pressure occupies 500 mL at 25.0 C. (a) What volume will the sample occupy at 0.0 C? (Assume that P and n are constant.) (b) What volume will the sample occupy at 200 C and 3.00 atm? (Assume that n is constant.) 13. A gas sample is originally at 0.0 C. At what temperature will the volume of this sample be twice as large as it was at 0 C if P is constant? 14. A gas sample occupies 30.0 L at 730 mmHg and 25°C. What would be the new volume at 700. mmHg and 20°C? 15. A gas sample occupies 30.0 L at 730 mmHg and 25°C. What would be the new volume at 500. mmHg? 16. If 11.8 L of propane, C3H8, are completely combusted, how many grams of water will be formed? Problem Set 4 1. a. What volume would 3.25 moles of helium gas occupy at STP? b. Carbon dioxide’s molar mass is roughly eleven times that of helium’s molar mass. What volume would 3.25 moles of CO2 occupy at STP? c. How many moles of oxygen gas are present in a 5.00 L gas sample that is at room conditions? (Note that the molar volume of a gas at 25 C and 1 atm is 24.5 Liters. You need to know this value for the quiz!) 2. How many moles of gas are present in each of the following samples: (a) 120 g of a gas occupying 89.6 Liters measured at STP, (b) 245 g of a gas occupying 122 Liters measured at 25 C and 1 atm? (c) What is the molecular weight of each gas? (Note that the molar volume of a gas at 25 C and 1 atm is 24.5 Liters. You need to know this value for the quiz!) 3. 5.00 grams of a gas occupy 2.55 L at STP. a. What must be the molar mass of this gas? b. How much space would this same gas occupy at room conditions? 4. 5. a. What’s the density of oxygen gas at STP? b. What’s the density of oxygen gas at room conditions? (Hint: density = mass/volume; density is independent of sample size; assume a convenient sample size (either 1.0 L OR 1.00 mol) to solve. c. What’s the density of oxygen gas at 50.°C and 1 atm? (Hint: Use Charles’ law to determine the molar volume of hydrogen at 50.°C.) A CO2 fire extinguisher contains about 4.4 kg of CO2. a. What volume of gas could this extinguisher deliver at 25 C and 1 atm? (Don’t make this complicated. It’s just a 3-step mole method problem – except you’ve been given kg instead of g.) b. What volume would this occupy at 0° C and 1 atm? C. What volume would this occupy at 20° C and 1 atm? 6. a. What is Avogadro’s hypothesis? b. Why was it important in getting relative weights for different kinds of molecules? 7. a. What volume does one mole of a gas occupy at standard temp. and pressure (0°C, 1 atm)? b. What is the name of this quantity? c. How many molecules are there in the value described in part a? 8. A 10.00 g sample of a gas occupies 2.00 Liters at STP. What is the molar mass of the gas? (Multiple choice question) A. 5.5 g/mol B. 55 (no units) C. 112 g/mol D. 220 (no units) E. 44.8 g/mol F. None of these Problem Set 5 – Note: 1. There is a table to water Clean dry air has a molecular composition as follows: N2 = 78.1%, O2 = 21.0%, and Ar = 0.9%. The barometer in the room reads 640. mm Hg. What is the partial pressure of .N2 in the room? 2. A mixture of gases contains 0.60 g H2, 4.4 g CO2, and 0.80 g He. The total pressure is 1.3 atm. (a) What is the partial pressure of each gas? (b) If the CO2 is solidified and then removed and the other gases are warmed to their original temperature, what is the new total pressure of the remaining gases and (c) After the CO2 is removed, what is the partial pressure of each remaining gas? (Assume that there is no interaction among the gases.) 3. What is the partial pressure of dry hydrogen gas, if the hydrogen gas is collected by water displacement at 25.5 oC? The “wet” hydrogen gas exerts a total pressure of 845.0 torr. (Hint: you will need to refer to your partial pressure of water table, which is attached to this assignment packet.) 4. A mixture of gases contains 2.00 moles CO2, 1.00 moles N2, and 3.00 moles N2O gases. If the total pressure of the gas mixture is 1000. mmHg, what is the partial pressure of each gas? 5. A mixture of gases contains 2.00 g CO2, 1.00 g N2, and 3.00 g N2O gases. If the total pressure of the gas mixture is 1000. mmHg, what is the partial pressure of each gas? 6. Students collect 50.0 mL of CO2 gas by water displacement. Room temperature and pressure are 22.0°C and 735 mmHg respectively. What’s the partial pressure of the CO2 gas? 7. 35.0 mL of hydrogen gas are collected over water at 735.5 mmHg and 20.0 °C. a. What pressure does the dry hydrogen exert (what is the partial pressure of hydrogen)? b. How much space would the dry hydrogen occupy at 40.0 °C, 1 atm? 8. How many grams of sodium would be required to synthesize 50.0 grams of sodium oxide from its elements? Problem Set 6 1. Compressed oxygen is sold in 40.0-litre steel cylinders. The pressure at 25.0 C is 130 atm. (a) How many moles does such a filled cylinder contain? (b) What is the mass of the 0 2 in the cylinder? (Hint: The ideal gas law is useful.) 2. Calculate R from the following data. Give units in both cases. (a) P = 760 mm, V = 12.2 Liters, T = 298 K, n = 0.500, (b) P = 108 cm, V = 3.36 Liters, mass of gas = 3.03 g, molecular weight of gas = 2.02 g/mole, T = 38.6 K 3. At what temperature is a gas sample stored at if the 1.50 moles sample occupies 8.50 L and exerts a pressure of 1200.0 torr? 4. What is the density of a 10.0 gram gas sample if the gas is stored in a 1.00 L gas cylinder at 15.0 oC and exerts a pressure of 4.75 atm? 5. (a) A 5.0 L gas sample (@ STP) has a mass of 1.80 g. What is the density of the gas in grams per liter? (b) What is the molecular weight of the gas? 6. a. What’s the density of oxygen gas at room conditions? b. What’s the density of oxygen gas at 30.°C, 735 mmHg? 7. When hydrogen is needed in the laboratory, it is commonly made by the reaction of zinc metal with hydrochloric acid (HCl). The products of the reaction are hydrogen gas and zinc chloride. (a) Write the balanced equation for the reaction. (b) How many moles of zinc must be used to produce 10.0 Liters of hydrogen gas measured at 18°C, 725 mm Hg? (c) How many grams of zinc would be necessary to produce the 10.0 Liters of hydrogen gas at these conditions? 8. Metallic silver can be reclaimed from silver chloride by the following reaction: AgCl + H 2 Ag + HCl. (a) Balance the equation. (b) What volume of hydrogen, measured at 20. C and 730. mmHg, would be used in changing 28.7 g of AgCl back to metallic silver? 9. a. What volume of carbon dioxide can be produced from 45.0 L of ethene? C2H4 (g) + 3 O2 (g) 2 CO2 (g) + 2 H2O (g) b. Why is it possible to calculate the previous problem without knowing the temperature and pressure the gas sample? TABLE - Water Vapor Pressure Temperature (°C) 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 Pressure (mm Hg) 12.8 13.6 14.5 15.5 16.5 17.5 18.6 19.8 Figure 1: 150. mmHg 710. mmHg Temperature (°C) 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 Pressure (mm Hg) 21.0 22.4 23.7 25.2 26.7 28.3 30/0 31.8 200. mmHg

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