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Key Concepts PowerPoint

## Chapter 8Thermochemistry: Chemical Energy

08-01
 Title Conservation of Energy Caption Figure 8.1 Conservation of energy. The total amount of energy contained by the water in a reservoir is constant. (a) At the top of the dam, the energy is potential (EP). (b)-(c) As the water falls over the dam, its velocity increases, and potential energy is converted into kinetic energy (EK). (d) At the bottom of the dam, the kinetic energy gained by the water is largely converted into heat and sound as the water dashes against the rocks. Notes Potential energy and kinetic energy Keywords potential energy, kinetic energy
08-02
 Title System and Surroundings Caption Figure 8.2 When energy changes are measured in a chemical reaction, the system is the reaction mixture being studied, and the surroundings are the flask, the room, and the rest of the universe. The energy change is the difference between final and initial states (DE = Efinal -Einitial). Any energy that flows from the system to the surroundings has a negative sign because Efinal is smaller than Einitial, and any energy that flows into the system from the surroundings has a positive sign because Efinal is larger than Einitial. Notes Flow of energy between system and surroundings Keywords energy, system, surroundings
08-04
 Title Expansion Work Caption Figure 8.4 The expansion in volume that occurs during a reaction forces the piston outward against atmospheric pressure P. The amount of work done is equal to the pressure exerted in moving the piston (the opposite of atmospheric pressure, -P) times the volume change (DV). The volume change is equal to the area of the piston (A) times the distance the piston moves (d). Thus, w = -PDV. Notes Work done during expansion Keywords work, expansion, pressure
08-04-03UN
 Title Key Concept Problem 8.4 Caption How much work is done (in kilojoules), and in which direction, as a result of the following reaction? Notes Key concept problem 8.4 Keywords key concept, work
08-04-06UN
 Title Key Concept Problem 8.5 Caption Work and enthalpy. Notes Key concept problem 8.5 Keywords key concept, work, enthalpy
08-04-07UN
 Title Trinitrotoluene Caption Ball-and-stick structure of trinitrotoluene (TNT). Notes For problem 8.7 Keywords trinitrotoluene, TNT, work
08-05
 Title Enthalpy as a State Function Caption Figure 8.5 Because enthalpy is a state function, the enthalpy change from solid to vapor does not depend on the path taken between the two states. Therefore, DHsubl = DHfusion +DHvap. Notes Enthalpy of sublimation, fusion, and vaporization Keywords ethalpy, state function, sublimation, fusion, vaporization
08-08
 Title Diagram of a Calorimeter Caption Figure 8.8 A calorimeter for measuring the heat flow in a reaction at constant pressure (DH). The reaction takes place inside an insulated vessel outfitted with a loose-fitting top, a thermometer, and a stirrer. Measuring the temperature change that accompanies the reaction makes it possible to calculate DH. Notes Calorimeter for measuring heat flow in a reaction Keywords calorimeter, calorimetry
08-09
 Title Bomb Calorimeter Caption Figure 8.9 A bomb calorimeter for measuring the heat evolved at constant volume in a combustion reaction (DE). The reaction is carried out inside a steel bomb, and the heat evolved is transferred to the surrounding water, where the temperature rise is measured. Notes Bomb calorimetry for measuring heat evolved from a combustion reaction Keywords bomb calorimeter, calorimetry, combustion
08-10
 Title Enthalpy of Formation of Ammonia Caption Figure 8.10 A representation of the enthalpy changes for steps in the synthesis of ammonia from nitrogen and hydrogen. If DH° values for step 2 and for the overall reaction are known, then DH° for step 1 can be calculated. That is, the enthalpy change for the overall reaction is equal to the sum of the enthalpy changes for the individual steps 1 and 2, a statement known as Hess’s law. Notes Enthalpy changes for steps in the synthesis of ammonia from nitrogen and hydrogen Keywords Hess's law, enthalpy
08-10-01UN
 Title Methylene chloride Caption Ball-and-stick structure of methylene chloride. Notes Problem 8.13 Keywords methylene chloride
08-10-02UN
 Title Key Concept Problem 8.14 Caption Hess's law diagram. Notes Key concept problem 8.14 Keywords key concept, Hess's law, enthalpy
08-11
 Title Using Standard Heats of Formation Caption Figure 8.11 The standard reaction enthalpy, DH°, for the generalized reaction A --> B is the difference between the standard heats of formation of products and reactants. Since the different heats of formation are referenced to the same point (the constituent elements), they are referenced to each other. Notes Standard enthalpy of reaction is equal to the difference in the standard heats of formation for the reactants and the products. Keywords reaction enthalpy, heat of formation
08-11-02UN
 Title Ethyl alcohol Caption Ball-and-stick structure of ethyl alcohol. Notes Problem 8.18 Keywords ethyl alcohol
08-12
 Title Products from Petroleum Refining Caption Figure 8.12 The products of petroleum refining. The different fractions are grouped according to the number of carbon atoms their molecules contain. Notes Products from petroleum refining Keywords petroleum refining
08-12-01UN
 Title Butane Caption Ball-and-stick structure of butane. Notes Problem 8.20 Keywords butane
08-13
 Title Entropy and Phase Changes Caption Figure 8.13 Entropy is a measure of molecular randomness, or disorder. Gases have more randomness and higher entropy than liquids, which in turn have more randomness and higher entropy than solids. Notes Entropy as a measure of randomness, or disorder, in a system. Keywords entropy, disorder
08-13-02UN
 Title Key Concept Problem 8.22 Caption Is the reaction represented by the diagram likely to have a positive or negative change in entropy? Notes Key concept problem 8.22 Keywords key concept, entropy
08-13-03UN
 Title Gibbs free-energy change Caption Equation for calculating the free-energy change determines whether a process is spontaneous or nonspontaneous at a given temperature; previously encountered thermodynamic terms, enthalpy and entropy, are involved in determining the free-energy change. Notes Calculating Gibbs free-energy change for a process Keywords Gibbs free-energy, free energy, spontaneity
08-15
 Title Spontaneity of a Phase Change Caption Figure 8.14 The melting of ice is disfavored by enthalpy (+DH) but favored by entropy (+DS). The freezing of water is favored by enthalpy (-DH) but disfavored by entropy (-DS). Below 0°C, the enthalpy term DH dominates the entropy term TDS in the Gibbs free-energy equation, so freezing is spontaneous. Above 0°C, the entropy term dominates the enthalpy term, so melting is spontaneous. At 0°C, the entropy and enthalpy terms are in balance. Notes Is the melting of ice or freezing of ice a spontaneous process? Keywords free-energy, spontaneity, phase change
08-15-01UN
 Title Diagram for Key Concept Example 8.13 Caption What are the signs of each of the thermodynamic terms for the nonspontaneous process represented by the diagram? Notes Key concept example 8.13 Keywords key concept, enthalpy, entropy, free-energy
08-15-02UN
 Title Key Concept Problem 8.25 Caption Diagram represents an exothermic reaction; what are the signs of each of the thermodynamic terms for this system? Notes Key concept problem 8.25 Keywords key concept, enthalpy, entropy, free-energy
08-15-030UN
 Title Key Concept Summary Caption Thermochemistry: chemical energy key concept summary. Notes Key concept summary Chapter 8 Keywords key concept, summary
08-15-04UN
 Title Diagram for Problem 8.26 Caption Work and enthalpy. Notes Problem 8.26 Keywords key concept, work, enthalpy
08-15-06UN
 Title Diagram for Problem 8.28 Caption Apply Hess's law to the reaction between acetylene and hydrogen gas. Notes Key concept problem 8.28 Keywords key concept, Hess's law, enthalpy
08-15-08UN
 Title Diagram for Problem 8.31 Caption Gibbs free-energy and spontaneity. Notes Key concept problem 8.31 Keywords key concept, free-energy, spontaneity
08-15-09UN
 Title Diagram for Problem 8.32 Caption What are the signs of the thermodynamic terms for the spontaneous process represented by the diagram? Notes Key concept problem 8.32 Keywords key concept, enthalpy, entropy, free-energy
08-15-10UN
 Title Diagram for Problem 8.33 Caption What are the signs of the thermodynamic terms for the spontaneous reaction represented by the diagram? Notes Key concept problem 8.33 Keywords key concept, enthalpy, entropy, free-energy
08-TB01
 Title Table 8.1 Specific Heats and Molar Heat Capacities for Some Common Substances at 25°C Caption Notes Keywords
08-TB02
 Title Table 8.2 Standard Heats of Formation for Some Common Substances at 25°C Caption Notes Keywords
08-TB03
 Title Table 8.3 Thermochemical Properties of Some Fuels Caption Notes Keywords
08-TB04
 Title Table 8.4 Caloric Values of Some Foods Caption Notes Keywords

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