Hood River Valley High

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1 Chemistry Hood River Valley High Name: Period: Unit 7 States of Matter and the Behavior of Gases Unit Goals- As you work through this unit, you should be able to: 1. Describe, at the molecular level, the difference between a gas, liquid, and solid phase. 2. Explain gas behavior using the kinetic molecular theory. 3. Relate attractive forces to boiling points and vapor pressure. 4. Interpret a phase diagram and describe the significance of the triple point. 5. Describe the four variables that define a gaseous system quantitatively 6. Use STP to determine the amount of gas used or produced in a chemical reaction. 7. Use ideal gas behavior and solve the following gas laws: Charles's Law Combined Gas Law Boyle's Law Ideal Gas Law Gay-Lussac s Law 8. Understand how gas mixtures and movements are described by the following gas laws: Dalton s Law of Partial Pressures & Graham s Law Assignments: Activities, Labs & Test Description Goals Gas Variable Candle Lab A1 Kinetic Molecular Theory WS 1 2 Charles Law Lab Boyles Lab A2 A3 A4 Relationship b/w gases & liquids WS Boyle s, Charles, Gay-Lussac s Law WS Combined and Ideal Gas Law WS Ideal & Part. Press. Lab Egg Suck and Shoot 4 Variable Lab Unit 7 Test Late Lab Stamp (this stamp means you are not qualified to do lab and test corrections) A5 Dalton s and Graham s Law WS 8 A6 Unit 7 Review 1-8 Readings: Ch. 13: (pp , ) Sections 13.1, 13.2, 13.4, Ch. 14: (pp ) Sections Key Terms: kinetic molecular theory, pressure, barometer, absolute temperature scale, vapor pressure, forces of attraction, normal boiling point, sublimation, phase diagram, triple point, normal freezing point,avogadro's Hypothesis, standard temperature and pressure, Charles's Law, Boyle's Law, Graham's Law, Combined Gas Law, ideal gas, Ideal Gas Law, Dalton's Law of Partial Pressure Demo s: See Demo Packet

2 Goal 1: States of Matter Chapter 13 Forces between particles of a substance. Intermolecular Forces. Hold particles together. Energy of Motion. Related to mass and speed of particles KE = ½ mv 2 Measure of Average Kinetic Energy of a sample. As temperature increases, particles move faster in a sample Collisions between atoms and molecules are ELASTIC. This means Kinetic Energy is conserved. TEMPERATURE is NOT lost due to Collisions. Collisions result in PRESSURE Attractive Forces between Particles Volume & Compressibility SOLID LIQUID GAS Molecular Motion

3 13.1 The Nature of Gases Goal 2: Kinetic Molecular Theory Kinetic Theory and a Model for Gases: Page 420 Describes the MOTION of gas particles 3 Statements of the Theory 1. The particles in a gas are considered to be, with an insignificant volume: attractive or forces exist between them. 2. The particles of a gas travel in, constant, and motion. They travel in line paths that are of eachother. 3. All collisions between particles are perfectly (no kinetic energy is lost). The total energy of the gas particles remains. Kinetic Molecular Theory helps explain: PRESSURE, VOLUME, and TEMPERATURE Pressure Number of that take place. More collisions = More. Volume Space that take up. Particles will completely fill a with their motion. Kinetic Energy and Temperature Average Energy of Related to of particles. Greater Speed = Greater. Temperature Theory: Kelvin Scale Page 424 What is absolute 0? How was 0K found? Why use Kelvin? 13.2 The Nature of Liquids Goal 3: Attractive Force Affects (Vapor Pressure: Page 427) The pressure caused by gas particles pushing upon a liquid Stronger attractive forces result in Vapor pressures At temperatures vapor pressure increases More molecules evaporate at temperatures Water: vapor pressure

4 Boiling Point: Page 428 Temperature at which pressure equals pressure. The liquid goes beyond just at Boiling Point. Gas bubbles begin to form the liquid. attractive forces result in BP s Volatility Likelihood of a liquid. Volatility: Liquid has vapor pressure Liquid is likely to evaporate produce vapor High Volatility: Liquids with attractive forces Water: volatility Surface Tension force (pull) between the of a liquid on the. High Surface Tension: Holds a liquid into. Liquids with very attractive forces have surface tension Water: surface tension

5 13.4 Changes of State Goal 4: Phase Diagrams: Page 438 Triple Point Chapter Goal 5: Gas Variables 4 variables define a gas system Pressure: (P) Units:» Pascal (Pa)» Atmospheres (atm)» Millimeters of Mercury (mm Hg)» Volume: (V) Units:» Liters (L), milliliters (ml), (cm 3 ) Temperature: (T) Units:» Celsius ( C)» Kevin (K)» Kelvin is the Official Unit» Number of Particles: (n) Unit: Moles (mol)

6 Goal 6: Gases and Moles review At STP: 1mol = 22.4L STP: Standard Temperature and Pressure»» Review 1 mol = 1 mol = 1 mol = Stoichiometry Examples Li 3 N (g) + 3H 2 O (l) NH 3(g) + 3LiOH (aq) What mass of water is needed to react with 29.3 L of Li 3 N? When 13.3 L of NH 3 are produced how many formula units of LiOH are produced? Given 7.8 moles of LiOH produced, what volume of Li 3 N was used? Math Review (k = constant) Direct Relationship Generic Equation Y = kx (k is a constant) k = Y/X Graph Inverse Relationship Generic Equation Y = k/x (k is a constant) k = XY Graph

7 14.2 The Gas Laws Goal 7: Gas Laws Boyles: Charles: Gay-Lussac s: Combined: Boyles Law: At constant TEMPERATURE: Pressure and Volume are INVERSE PV = constant P 1 V 1 = P 2 V 2 Graph of P vs. V: As Pressure increases Volume Practice Boyles Law #1: Nitrous oxide (N 2 O) is used as an anesthetic. The pressure on 2.50 L of N 2 O changes from 105 kpa to 40.5 kpa. If the temperature does not change, what will the new volume be? Practice Boyles Law #2: A gas with a volume of 4.00 L at a pressure of 205 kpa is allowed to expand to a volume of 12.0 L. What is the pressure in the container if the temperature remains constant? Charles Law: At constant PRESSURE: Temperature and Volume are DIRECT V/T = constant Graph of V vs. T: As Temperature increases Volume

8 Practice Charles Law #1: A balloon inflated in a room at 24⁰C has a volume of 4.00 L. The balloon is then heated to a temperature of 58⁰C. What is the new volume if the pressure remains the same? (pg 459) Practice Charles Law #2: If a sample of gas in a balloon occupies 6.8 L at 325 C, what is the temperature if the volume later is found to be 4.2L if the pressure does not change? Gay-Lussac s Law: Page 460 At constant VOLUME: Temperature and Pressure are DIRECT P/T = constant Graph of P vs. T: As Temperature increases Pressure Practice Gay-Lussac s #1: Aerosol cans carry labels warning not to incinerate (burn) the cans or store them above a certain temperature. This problem will show why it is dangerous to dispose of aerosol cans in a fire. The gas in a used aerosol can is at a pressure of 103 kpa at 25⁰C. If the can is thrown onto a fire, what will the pressure be when the temperature reaches 928⁰C? Practice Gay-Lussac s #2: The pressure iin a car tire is 198 kpa at 27 ⁰C. After a long drive, the pressure is 225 kpa. What is the temperature of the air in the tire? Assume that the volume is constant. Combined Gas Laws: Page 462 All 3 laws put together

9 Practice Combined #1: The volume of a gas-filled balloon is 30.0 L at 313 K and 153 kpa pressure. What would the volume be at STP? (pg 462) Practice Combined #2: A gas at 155 kpa and 25 C occupies a container with an initial volume of L. By changing the temperature, the pressure of a gas increases to 605 kpa and the volume increases to 2.4 L. What is the new temperature? Practice Combined #3: A 5.00 L air sample at a temperature of 50 C has a pressure of 107 kpa. What is the new pressure if the temperature is raised to 102 C and the volume expands to 7.00 L? 14.3 Ideal Gases Ideal Gas Law: Page 464: Ideal Gas Law includes number of into the calculation. How does it work? n = P: V: T: n: R: If kpa, R = If atm, R = If mmhg, R = Ideal Gas Law PV=nRT Example 1: You fill a rigid steel cylinder that has a volume of 20.0 L with nitrogen gas to a final pressure of 20,000.0 kpa at 28 C. How many moles of nitrogen gas does the cylinder contain?

10 PV=nRT Example 2: Deep underground cavern contains 2.24 x 10^6 L of methane gas, CH 4, at a pressure of 1.5 x 10^3 kpa and a temperature of 42 C. How many grams of methane does this naturalgas deposit contain? PV=nRT Example 3: What volume will 12 grams of oxygen gas occupy at 25 C and a pressure of 52.7 kpa? PV=nRT Example 4: When the temperature of a rigid hollow sphere containing 68.5 moles of helium gas is held at 621 L, the pressure of the gas is 1.89 x 10 3 kpa. What temperature is this container of helium? PV=nRT Example 5: What pressure will be exerted by 0.45 mol of a gas at 25 C if it is contained in a 0.65 L vessel? 14.4 Gases: Mixtures and Movements Dalton s Law: Page 469, Goal 8: The total pressure of a gas is the of the pressures of each gas in the mixture P t = Each gas pressure depends on its % Mole Ratio s and % abundance

11 Dalton Law Examples #1: A container has a mixture of atmosphere and water vapor. At 50 C the partial pressure of water vapor is kpa. What is the pressure of the atmosphere gasses if the total pressure is kpa? Dalton Law Examples #2: A container contains 10 g of oxygen gas, 80 g of nitrogen gas and 1 g of carbon dioxide. The total pressure of the container is kpa, find: Mole fraction of each gas The partial pressure of each gas Graham s Law: Page 472 The velocity of particles is related to their temperature (ave. Kinetic Energy) and their mass. KE = ½ mv 2 Therefore v = v is inversely proportional to the mass of the particle at any given temperature. For 2 gases (A and B) Graham Law Applications At the SAME Molecules with masses have velocities Molecules with masses have velocities DIFFUSION: The tendency of molecules to move toward areas of concentration. Molecules with greater have rates of diffusion 2 effects on Diffusion rates: 1. 2.

12 Graham s law Example 1: Compare the rate of diffusion of nitrogen gas to helium gas: Graham s law Example 2: Compare the rate of diffusion of argon to neon gas: Graham s law Example 3: What is the rate of effusion for a gas that has a molar mass twice that of a gas that effuses at a rate of 3.62 mol/min? Graham s law Example 4: An unknown gas effuses 1.66 times more rapidly than CO 2. What is the molar mass of the unknown gas.