1. Figure 05-02
Title:
Potential energy and kinetic energy.
Caption:
(a) A bicycle at the top of a hill has a high potential energy relative to the bottom of the hill. (b) As the bicycle proceeds down the hill, the potential energy is converted into kinetic energy.
Notes:
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Figure 05.02

2. Figure 05-03
Title:
A closed system and its surroundings.
Caption:
Hydrogen and oxygen gases are confined in a cylinder with a movable piston. If we are interested only in the properties of these gases, the gases are the system and the cylinder and piston are part of the surroundings. Because the system can exchange energy (in the form of heat and work) but not matter with its surroundings, it is a closed system.
Notes:
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Figure 05.03

3. Figure 05-04
Title:
Changes in internal energy.
Caption:
(a) When a system loses energy, that energy is released to the surroundings. The loss of energy is represented by an arrow that points downward between the initial and final states of the system. In this case, the energy change of the system, ΔE = Efinal – Einitial, is negative. (b) When a system gains energy, that energy is gained from the surroundings. In this case, the gain of energy is represented by an arrow that points upward between the initial and final states of the system, and the energy change of the system is positive. Notice in both (a) and (b) that the vertical arrow originates at the initial state and has its head at the final state.
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Figure 05.04

4. Figure 05-04a
Title:
Changes in internal energy.
Caption:
(a) When a system loses energy, that energy is released to the surroundings. The loss of energy is represented by an arrow that points downward between the initial and final states of the system. In this case, the energy change of the system, ΔE = Efinal – Einitial, is negative. (b) When a system gains energy, that energy is gained from the surroundings. In this case, the gain of energy is represented by an arrow that points upward between the initial and final states of the system, and the energy change of the system is positive. Notice in both (a) and (b) that the vertical arrow originates at the initial state and has its head at the final state.
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Figure 05.04a

5. Figure 05-05
Title:
Energy diagram for the interconversion of H2(g), O2(g), and H2O(l).
Caption:
A system composed of H2(g) and O2(g) has a greater internal energy than one composed of H2O(l). The system loses energy (ΔE < 0) when H2 and O2 are converted to H2O. It gains energy (ΔE > 0) when H2O is decomposed into H2 and O2.
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Figure 05.05

6. Figure 05-06
Title:
Sign conventions for heat and work.
Caption:
Heat, q, gained by a system and work, w, done on a system are both positive quantities. Both increase the internal energy, E, of the system, causing ΔE to be a positive quantity.
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Figure 05.06

7. Figure 05-07
Title:
Examples of endothermic and exothermic reactions.
Caption:
(a) When ammonium thiocyanate and barium hydroxide octahydrate are mixed at room temperature, an endothermic reaction occurs: 2 NH4SCN(s) + Ba(OH)2 * 8 H2O(s) → Ba(SCN)2(aq) + 2 NH3(aq) + 10 H2O(l). As a result, the temperature of the system drops from 20 °C about to -9 °C. (b) The reaction of powdered aluminum with Fe2O3 (the thermite reaction) is highly exothermic. The reaction proceeds vigorously to form Al2O3 and molten iron: 2 Al(s) + Fe2O3(s) → Al2O3(s) + 2 Fe(l ).
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Figure 05.07

8. Figure 05-08
Title:
Internal energy, E, a state function.
Caption:
E depends only on the present state of the system and not on the path by which it arrived at that state. The internal energy of 50 g of water at 25 °C is the same whether the water is cooled from a higher temperature to 25 °C or warmed from a lower temperature to 25 °C.
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Figure 05.08

9. Figure 05-09
Title:
Internal energy is a state function, but heat and work are not.
Caption:
The amounts of heat and work transferred between the system and the surroundings depend on the way in which the system goes from one state to another. (a) A battery shorted out by a wire loses energy to the surroundings only as heat; no work is performed by the system. (b) A battery discharged through a motor loses energy as work (to make the fan turn) and also loses energy as heat. Now, however, the amount of heat lost is much less than in (a). The value of ΔE is the same for both processes even though the values of q and w in (a) are different from the values of q and w in (b).
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Figure 05.09

10. Figure 05-10
Title:
A system that does work on its surroundings.
Caption:
(a) An apparatus for studying the reaction of zinc metal with hydrochloric acid at constant pressure. The piston is free to move up and down in its cylinder to maintain a constant pressure equal to atmospheric pressure inside the apparatus. Notice the pellets of zinc in the L-shaped arm on the left. When this arm is rotated, the pellets will fall into the main container and the reaction will begin. (b) When zinc is added to the acid solution, hydrogen gas is evolved. The hydrogen gas does work on the surroundings, raising the piston against atmospheric pressure to maintain constant pressure inside the reaction vessel.
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Figure 05.10

11. Figure 05-10a
Title:
A system that does work on its surroundings.
Caption:
(a) An apparatus for studying the reaction of zinc metal with hydrochloric acid at constant pressure. The piston is free to move up and down in its cylinder to maintain a constant pressure equal to atmospheric pressure inside the apparatus. Notice the pellets of zinc in the L-shaped arm on the left. When this arm is rotated, the pellets will fall into the main container and the reaction will begin.
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Figure 05.10a

12. Figure 05-11
Title:
Endothermic and exothermic processes.
Caption:
(a) If the system absorbs heat (endothermic process), ΔH will be positive (ΔH >0). (b) If the system loses heat (exothermic process), ΔH will be negative (ΔH < 0).
Notes:
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Figure 05.11

13. Figure 05-12
Title:
Pressure-volume work.
Caption:
A piston moving upward, expanding the volume of the system against an external pressure, P, does work on the surroundings. The amount of work done by the system on the surroundings is w = - P Δ V.
Notes:
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Figure 05.12

14. Figure 05-13a
Title:
Exothermic reaction of hydrogen with oxygen.
Caption:
(a) A candle is held near a balloon filled with hydrogen gas and oxygen gas.
Notes:
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Figure 05.13a

15. Figure 05-13ab
Title:
Exothermic reaction of hydrogen with oxygen.
Caption:
(a) A candle is held near a balloon filled with hydrogen gas and oxygen gas. (b) The H2(g) ignites, reacting with O2(g) to form H2O(g). The resultant explosion produces a ball of flame. The system gives off heat to its surroundings.
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Figure 05.13ab

16. Figure 05-13
Title:
Exothermic reaction of hydrogen with oxygen.
Caption:
(a) A candle is held near a balloon filled with hydrogen gas and oxygen gas. (b) The H2(g) ignites, reacting with O2(g) to form H2O(g). The resultant explosion produces a ball of flame. The system gives off heat to its surroundings. (c) The enthalpy diagram for this reaction, showing its exothermic character.
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Figure 05.13

17. Figure 05-15
Title:
ΔH for a reverse reaction.
Caption:
Reversing a reaction changes the sign but not the magnitude of the enthalpy change: ΔH2 = -ΔH1.
Notes:
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Figure 05.15

18. Figure 05-16
Title:
Specific heat of water.
Caption:
Specific heat indicates the amount of heat that must be added to one gram of a substance to raise its temperature by 1 K (or 1 °C ). Specific heats can vary slightly with temperature, so for precise measurements the temperature is specified. The specific heat of H2O(l) at 14.5 °C is J/g-K; the addition of J of heat to 1 g of liquid water at this temperature raises the temperature to 15.5 °C. This amount of energy defines the calorie: 1 cal = J.
Notes:
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Figure 05.16

19. Figure 05-17
Title:
Coffee-cup calorimeter.
Caption:
This simple apparatus is used to measure heat-accompanying reactions at constant pressure.
Notes:
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Figure 05.17

20. Figure 05-18
Title:
Bomb calorimeter.
Caption:
This device is used to measure heat accompanying combustion reactions at constant volume.
Notes:
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Figure 05.18

21. Figure 05-20
Title:
An enthalpy diagram comparing a one-step and a two-step process for a reaction.
Caption:
The enthalpy change of the direct reaction on the left equals the sum of the two steps on the right. That is, ΔH for the overall reaction equals the sum of the ΔH values for the two steps shown.
Notes:
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Figure 05.20

22. Figure 05-20a
Title:
An enthalpy diagram comparing a one-step and a two-step process for a reaction.
Caption:
The enthalpy change of the direct reaction on the left equals the sum of the two steps on the right. That is, ΔH for the overall reaction equals the sum of the ΔH values for the two steps shown.
Notes:
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Figure 05.20a

23. Figure 05-21
Title:
An enthalpy diagram illustrating Hess's law.
Caption:
Because H is a state function, the enthalpy change for the combustion of 1 mol CH4 is independent of whether the reaction takes place in one or more steps: ΔH1 = ΔH2 + ΔH3.
Notes:
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Figure 05.21

24. Figure 05-22
Title:
An enthalpy diagram relating the enthalpy change for a reaction to enthalpies of formation.
Caption:
For the combustion of propane gas, C3H8(g), the reaction is C3H8(g) + 5 O2 → 3 CO2(g) + 4 H2O(l). We can imagine this reaction as occurring in three steps. First, C3H8(g) is decomposed to its elements, so ΔH1 = ΔH°f[C3H8(g)]. Second, 3 mol CO2(g) are formed, so ΔH2 = 3ΔH[CO2](g). Finally, 4 mol H2O(l) are formed, so ΔH3 = 4ΔH[H2O](l). Hess's law tells us that ΔH°rxn = ΔH1 + ΔH2 + ΔH3. This same result is given by Equation 5.31 because ΔH°f[O2(g)] = 0
Notes:
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Figure 05.22

25. Figure 05-22a
Title:
An enthalpy diagram relating the enthalpy change for a reaction to enthalpies of formation.
Caption:
For the combustion of propane gas, C3H8(g), the reaction is C3H8(g) + 5 O2 → 3 CO2(g) + 4 H2O(l). We can imagine this reaction as occurring in three steps. First, C3H8(g) is decomposed to its elements, so ΔH1 = ΔH°f[C3H8(g)]. Second, 3 mol CO2(g) are formed, so ΔH2 = 3ΔH[CO2](g). Finally, 4 mol H2O(l) are formed, so ΔH3 = 4ΔH[H2O](l). Hess's law tells us that ΔH°rxn = ΔH1 + ΔH2 + ΔH3. This same result is given by Equation 5.31 because ΔH°f[O2(g)] = 0
Notes:
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Figure 05.22a

26. Figure 05-22b
Title:
An enthalpy diagram relating the enthalpy change for a reaction to enthalpies of formation.
Caption:
For the combustion of propane gas, C3H8(g), the reaction is C3H8(g) + 5 O2 → 3 CO2(g) + 4 H2O(l). We can imagine this reaction as occurring in three steps. First, C3H8(g) is decomposed to its elements, so ΔH1 = ΔH°f[C3H8(g)]. Second, 3 mol CO2(g) are formed, so ΔH2 = 3ΔH[CO2](g). Finally, 4 mol H2O(l) are formed, so ΔH3 = 4ΔH[H2O](l). Hess's law tells us that ΔH°rxn = ΔH1 + ΔH2 + ΔH3. This same result is given by Equation 5.31 because ΔH°f[O2(g)] = 0
Notes:
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Figure 05.22b

27. Figure 05-22c
Title:
An enthalpy diagram relating the enthalpy change for a reaction to enthalpies of formation.
Caption:
For the combustion of propane gas, C3H8(g), the reaction is C3H8(g) + 5 O2 → 3 CO2(g) + 4 H2O(l). We can imagine this reaction as occurring in three steps. First, C3H8(g) is decomposed to its elements, so ΔH1 = ΔH°f[C3H8(g)]. Second, 3 mol CO2(g) are formed, so ΔH2 = 3ΔH[CO2](g). Finally, 4 mol H2O(l) are formed, so ΔH3 = 4ΔH[H2O](l). Hess's law tells us that ΔH°rxn = ΔH1 + ΔH2 + ΔH3. This same result is given by Equation 5.31 because ΔH°f[O2(g)] = 0
Notes:
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Figure 05.22c

28. Figure 05-24
Title:
Sources of energy consumed in the United States.
Caption:
In 2005 the United States consumed a total of 1.05 x 1017 kJ of energy.
Notes:
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Figure 05.24

29. Figure 05-26
Title:
Schematic diagram of a mild hybrid car.
Caption:
The 48-volt battery pack provides energy for operating several auxiliary functions. It is recharged from the engine and through the braking system.
Notes:
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Figure 05.26

30. Figure UNEOC
Title:
Visualizing Concepts 5.2
Caption:
Consider the accompanying energy diagram. (a) Does this diagram represent an increase or decrease in the internal energy of the system? (b) What sign is given to ΔE for this process? (c) If there is no work associated with the process, is it exothermic or endothermic? [Section 5.2]
Notes:
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Figure UNEOC

31. Figure UNEOC
Title:
Visualizing Concepts 5.3
Caption:
The contents of the closed box in each of the following illustrations represent a system, and the arrows show the changes to the system during some process. The lengths of the arrows represent the relative magnitudes of q and w. (a) Which of these processes is endothermic? (b) For which of these processes, if any, is ΔE<0 ? (c) For which process, if any, is there a net gain in internal energy? [Section 5.2]
Notes:
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Figure UNEOC

32. Figure UNEOC
Title:
Visualizing Concepts 5.5
Caption:
In the cylinder diagrammed below, a chemical process occurs at constant temperature and pressure. (a) Is the sign of w indicated by this change positive or negative? (b) If the process is endothermic, does the internal energy of the system within the cylinder increase or decrease during the change and is ΔE positive or negative? [Sections 5.2 and 5.3]
Notes:
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Figure UNEOC

33. Figure UNEOC
Title:
Visualizing Concepts 5.6
Caption:
Imagine a container placed in a tub of water, as depicted in the accompanying diagram. (a) If the contents of the container are the system and heat is able to flow through the container walls, what qualitative changes will occur in the temperatures of the system and in its surroundings? What is the sign of q associated with each change? From the system's perspective, is the process exothermic or endothermic? (b) If neither the volume nor the pressure of the system changes during the process, how is the change in internal energy related to the change in enthalpy? [Sections 5.2 and 5.3]
Notes:
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Figure UNEOC

34. Figure UNEOC
Title:
Visualizing Concepts 5.8
Caption:
A gas-phase reaction was run in an apparatus designed to maintain a constant pressure. (a) Write a balanced chemical equation for the reaction depicted, and predict whether w is positive, negative, or zero. (b) Using data from Appendix C, determine ΔH for the formation of one mole of the product. Why is this enthalpy change called the enthalpy of formation of the involved product? [Sections 5.3 and 5.7]
Notes:
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Figure UNEOC

35. Figure UNEOC
Title:
Visualizing Concepts 5.9
Caption:
Consider the two diagrams. (a) Based on (i), write an equation showing how ΔHA is related to ΔHB and ΔHC. How do both diagram (i) and your equation relate to the fact that enthalpy is a state function? (b) Based on (ii), write an equation relating ΔHZ to the other enthalpy changes in the diagram. (c) How do these diagrams relate to Hess's law? [Section 5.6]
Notes:
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Figure UNEOC

36. Figure UNEOC
Title:
Exercise 5.18
Caption:
In a thermodynamic study a scientist focuses on the properties of a solution in an apparatus as illustrated. A solution is continuously flowing into the apparatus at the top and out at the bottom, such that the amount of solution in the apparatus is constant with time. (a) Is the solution in the apparatus a closed system, open system, or isolated system? Explain your choice. (b) If it is not a closed system, what could be done to make it a closed system?
Notes:
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Figure UNEOC

37. Figure UNEOC
Title:
Exercise 5.26
Caption:
For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (a) A balloon is heated by adding 850 J of heat. It expands, doing 382 J of work on the atmosphere. (b) A 50-g sample of water is cooled from 30 °C to 15 °C, thereby losing approximately 3140 J of heat. (c) A chemical reaction releases 6.47 kJ of heat and does no work on the surroundings.
Notes:
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Figure UNEOC

38. Figure UNEOC
Title:
Exercise 5.28
Caption:
Consider a system consisting of two oppositely charged spheres hanging by strings and separated by a distance r1, as shown in the accompanying illustration. Suppose they are separated to a larger distance r2, by moving them apart along a track. (a) What change, if any, has occurred in the potential energy of the system? (b) What effect, if any, does this process have on the value ΔE?
Notes:
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Figure UNEOC

39. Figure UNEOC
Title:
Exercise 5.75
Caption:
Gasoline is composed primarily of hydrocarbons, including many with eight carbon atoms, called octanes. One of the cleanest-burning octanes is a compound called 2,3,4-trimethylpentane, which has the structural formula shown. The complete combustion of one mole of this compound to CO2(g) and H2O (g) leads to ΔH° = kJ/mol. (a) Write a balanced equation for the combustion of 1 mol of C8H18(l). (b) Write a balanced equation for the formation of C8H18(l) from its elements. (c) By using the information in this problem and data in Table 5.3, calculate ΔH°f for 2,3,4-trimethylpentane.
Notes:
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Figure UNEOC

40. Figure UNEOC
Title:
Additional Exercise 5.92
Caption:
A sample of gas is contained in a cylinder-and-piston arrangement. It undergoes the change in state shown in the drawing. (a) Assume first that the cylinder and piston are perfect thermal insulators that do not allow heat to be transferred. What is the value of q for the state change? What is the sign of w for the state change? What can be said about ΔE for the state change? (b) Now assume that the cylinder and piston are made up of a thermal conductor such as a metal. During the state change, the cylinder gets warmer to the touch. What is the sign of q for the state change in this case? Describe the difference in the state of the system at the end of the process in the two cases. What can you say about the relative values of ΔE?
Notes:
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Figure UNEOC

41. Figure 05-EOCT01
Title:
Exercise 5.104
Caption:
Prospective fuel data.
Notes:
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End of Chapter Table 05.01

42. Figure 05-EOCT02
Title:
Exercise 5.107
Caption:
Heats of formation of some common hydrocarbons containing four carbon atoms.
Notes:
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End of Chapter Table 05.02

43. Figure 05-T01
Title:
Table 5.1
Caption:
Sign Conventions for q, w, and ΔE.
Notes:
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Table 05.01

44. Figure 05-T02
Title:
Table 5.2
Caption:
Specific Heats of Some Substances at 298 K
Notes:
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Table 05.02

45. Figure 05-T03
Title:
Table 5.3
Caption:
Standard Enthalpies of Formation, ΔH°f, at 298 K
Notes:
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Table 05.03

46. Figure 05-T04
Title:
Table 5.4
Caption:
Compositions and Fuel Values of Some Common Foods
Notes:
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Table 05.04

47. Figure 05-T05
Title:
Table 5.5
Caption:
Fuel Values and Compositions of Some Common Fuels
Notes:
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Table 05.05