# Tuesday, Dec. 3 rd : “A” Day Wednesday, Dec. 4 th : “B” Day (early out) Agenda  Homework Questions/collect (pg. 398: 1-3, 6-9)  Sec. 11.3 quiz: “Energy.

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<ul><li> Slide 1 </li> <li> Slide 2 </li> <li> Slide 3 </li> <li> Tuesday, Dec. 3 rd : A Day Wednesday, Dec. 4 th : B Day (early out) Agenda Homework Questions/collect (pg. 398: 1-3, 6-9) Sec. 11.3 quiz: Energy of State Changes Section 11.4: Phase Equilibrium Phase, equilibrium, vapor pressure, phase diagram, triple point, critical point Homework: Pg 405: #1-5 Concept Review: Phase Equilibrium What Would Life be Like? paper </li> <li> Slide 4 </li> <li> Homework pg. 398: #1-3, 6-9 Questions? Problems? </li> <li> Slide 5 </li> <li> Section 11.3 Quiz Energy of State Changes You may use your notes, your book, and your lab partner to complete the quiz </li> <li> Slide 6 </li> <li> Two-Phase Systems System: a set of components that are being studied. Phase: a part of matter that is uniform (a region that has the same composition and properties throughout) For example, ice water is a system that has a solid phase and a liquid phase. </li> <li> Slide 7 </li> <li> Equilibrium Involves Constant Interchange of Particles Equilibrium: the state in which a chemical process and the reverse chemical process occur at the same rate such that the concentrations of reactants and products do not change. A dynamic equilibrium exists when particles are constantly moving between two or more phases yet no net change in the amount of substance in either phase takes place. </li> <li> Slide 8 </li> <li> Example If you open a bottle of rubbing alcohol, you can smell the alcohol. When you put the cap back on, an equilibrium between the liquid phase and the gas phase is quickly reached. That is, the rate of evaporation equals the rate of condensation. </li> <li> Slide 9 </li> <li> Vapor Pressure Increases with Temperature For an enclosed gas and liquid in equilibrium,like the rubbing alcohol, the gas particles above the liquid exert pressure when they strike the walls of the container. Vapor pressure: the partial pressure exerted by a vapor that is in equilibrium with its liquid state at a given temperature. The boiling point is the temperature at which the vapor pressure equals the external pressure. </li> <li> Slide 10 </li> <li> Vapor Pressure Increases with Temperature As you increase the temperature of a closed system, more liquid particles escape into the gas phase. Thus, as you increase temperature, the vapor pressure of the substance also increases. When you increase the temperature of a system to the point at which the vapor pressure of a substance is equal to standard atmospheric pressure have reached the substances normal boiling point. </li> <li> Slide 11 </li> <li> Vapor Pressure Increases with Temperature The dotted line represents atmospheric pressure and shows the normal boiling point. </li> <li> Slide 12 </li> <li> Phase Diagrams A substances phase depends on temperature and pressure. To get a complete picture of how temperature and pressure are related for a particular substance, you can look at a phase diagram. Phase diagram: a graph that shows the relationship between the physical state of a substance and the temperature and pressure of the substance. </li> <li> Slide 13 </li> <li> Phase Diagrams A phase diagram has three lines: One line shows the liquid-gas equilibrium. Another line shows the liquid-solid equilibrium A third line shows the solid-gas equilibrium. These three lines meet at the triple point. Triple point: the temperature and pressure conditions at which the solid, liquid and gaseous phases of a substance coexist at equilibrium. </li> <li> Slide 14 </li> <li> Phase Diagram for Water </li> <li> Slide 15 </li> <li> Phase Diagrams Relate State, Temperature, and Pressure For any given point (x, y) on a phase diagram, you can determine what the state of a substance will be. </li> <li> Slide 16 </li> <li> Gas-Liquid Equilibrium for Water Line AD shows liquid-vapor equilibrium. As you follow line AD upwards, the vapor pressure is increasing, so the density of the vapor increases and the density of the liquid decreases. Critical point: the temperature and pressure at which the gas and liquid states of a substance become identical and form one phase. Above this point, the substance is called a supercritical fluid. </li> <li> Slide 17 </li> <li> Solid-Liquid Equilibrium for Water Line AC shows solid-liquid equilibrium. Only solid is present to the left of line AC. Water is an unusual substance: the solid is less dense than the liquid. Why? Hydrogen bonding! The line AC has a slightly negative slope, which is very rare in phase diagrams of other substances. </li> <li> Slide 18 </li> <li> Solid-Gas Equilibrium for Water Line AB shows solid-vapor equilibrium. If the pressure is decreased below the line AB, the solid will sublime. Freeze-drying uses the process of sublimation of ice below the freezing point to dry foods. </li> <li> Slide 19 </li> <li> Phase Diagrams Are Unique to a Particular Substance Each pure substance has a unique phase diagram, although the general structure is the same. The triple point is characteristic for each substance and serves to distinguish the substance from other substances. Unlike boiling point, the melting point is affected little by changes in pressure, so the solid-liquid equilibrium line is nearly vertical in phase diagrams. </li> <li> Slide 20 </li> <li> Phase Diagram for CO 2 </li> <li> Slide 21 </li> <li> Notice that in the phase diagram for carbon dioxide, the horizontal line at 101.3 kPa does not intersect the solid-liquid line. Thats because carbon dioxide is never a liquid at standard pressure. At room temperature, solid carbon dioxide sublimes, or changes directly from a solid to a gas. </li> <li> Slide 22 </li> <li> Homework Section 11.4 Review, Pg. 405: #1-5 Concept Review: Phase Equilibrium What Would Life Be Like? Paper Due Mon/Tues *Lab next time* Chapter 11 Test/Concept Review Due: Friday, 12-13: A Day Monday, 12-16: B Day </li> </ul>