Chapter 19 Suggested Homework Answers

Chapter 19 Suggested Homework Answers - Chapter 19...

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Chapter 19 Suggested Homework Answers 8. A spontaneous process occurs by itself with no outside interference. A nonspontaneous process does not occur by itself. (a) The spreading of the fragrance of perfume through a room is a spontaneous process. (b) Separating a mixture of N 2 and O 2 into two separate pure samples of N 2 and O 2 is a nonspontaneous process. (c) The bursting of an inflated balloon is a spontaneous process. (d) The reaction of sodium metal with chlorine gas to form sodium chloride is a spontaneous process. (e) Dissolving HCl (g) in water to form concentrated hydrochloric acid is a spontaneous process. 12. (a) Freezing of a substance requires a withdrawal of heat. Therefore, it is an endothermic process. (b) Freezing of 1-propanol is spontaneous below the freezing point of –127°C. (c) Freezing of 1-propanol is nonspontaneous above the freezing point of –127°C. (d) Liquid and solid 1-propanol are in equilibrium at the freezing point of –127°C. 30. (a) If two gases combine to form a solid, the sign of S should be negative because gases have more entropy than solids. (b) In exercise 19.7, the melting of ice cubes would have a positive value of S because liquids have more entropy than solids. Dissolving sugar in hot coffee would have a positive value of S because dissolved sugar has more entropy than solid sugar. The reaction of nitrogen atoms to form nitrogen molecules would have a negative value of S because a collection of atoms have more entropy than a collection of molecules formed from the atoms. The alignment of iron filings in a magnetic field would have a negative value of S because the final state has more order. Formation of CH 4 (g) and O 2 (g) from CO 2 (g) and H 2 O (l) would have a positive value of S since all the products are gases and one of the reactants is a liquid. 32. (a) Entropy increases when the temperature is increased. (b) As the volume of a gas increases, its pressure will decrease. As pressure decreases, entropy increases. (c) As a solid dissolves in water, its entropy increases.
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39. (a) 2 SO 2 (g) + O 2 (g) → 2 SO 3 (g) Because you have 3 moles of gaseous reactants and 2 moles of gaseous products, S should be negative. (b) Ba(OH) 2 (s) → BaO (s) + H 2 O (g) Since you have a gaseous product and no gaseous reactants, S should be positive. (c) CO (g) + 2 H 2 (g) → CH 3 OH (l) Because you have gaseous reactants and only liquid products, S should be negative. (d) FeCl 2 (s) + H 2 (g) → Fe (s) + 2 HCl (g) Since you have 1 mole of gaseous reactants and 2 moles of gaseous products, S should be positive. 40. (a) Molten Fe solidifies. Since you have a liquid going to a solid,
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This note was uploaded on 04/16/2008 for the course PSYCH 230 taught by Professor Phillips during the Spring '08 term at Iowa State.

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Chapter 19 Suggested Homework Answers - Chapter 19...

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