Ch. 17 - Chemical ThermodynamicsWorksheetSee all chapters
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Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
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Ch.10 - Molecular Shapes & Valence Bond Theory
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Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Entropy is the disorder or chaos associated with a system’s inability to convert thermal energy into mechanical work. 

Entropy and Spontaneity

Concept #1: The 2nd and 3rd Laws of Thermodynamics

The 2nd Law of Thermodynamics states systems (chemical reactions) spontaneously move to state of disorder. 

Concept #2: Entropy & Phase Changes

During a phase change as our molecules grow farther apart then entropy will increase. 

During a phase change as our molecules grow closer together then entropy will decrease.

Example #1: Which should have the highest molar entropy at 25oC?

Example #2: Which substance has greater molar entropy. 

Entropy and Phases

When comparing the entropy of different compounds then we must follow a set of guidelines in the following order. 

Example #3: Arrange the following substances in the order of increasing entropy at 25oC. 

Example #4: Containers A and B have two different gases that are allowed to enter Container C. Based on the image of Container C, what is the sign of entropy, ΔS°.

Practice: An ideal gas is allowed to expand at constant temperature. What are the signs of ∆H, ∆S & ∆G.

Whenever a phase change occurs, first determine if bonds are broken or formed to figure out the signs of enthalpy and entropy. Afterwards, determine if the reaction is spontaneous to determine the sign of Gibbs Free energy. 

Example #5: Consider the spontaneous fusion of ice at room temperature. For this process what are the signs for ΔH, ΔS and ΔG?

Practice: Consider the freezing of liquid water at 30°C. For this process what are the signs for ∆H, ∆S, and ∆G?

If bonds are broken then the entropy of a reaction increases, but if bonds are formed then the entropy of a reaction decreases. 

Practice: Predict the sign of ∆S in the system for each of the following processes:

a) Ag+ (aq) + Br - (aq) → AgBr (s)

b) CI2 (g) → 2 CI - (g)

c) CaCO3 (s) → CaO (s) + CO2 (g)

d) Pb (s) at 50°C → Pb (s) at 70°C

Practice: For each of the following reactions state the signs of ∆H (enthalpy) and ∆S (entropy):

a) Fusion of ice.

b) Sublimation of CO2

c) Vaporization of aqueous water.

d) Deposition of chlorine gas.

e) Condensation of water vapor. 


 Entropy and Calculations

The 2nd Law of Thermodynamics states that the entropy of the universe is always increasing and so it must always be greater than zero. 

Concept #3: The Universe & Entropy

The entropy of the universe takes the look at the entropy of our system (the chemical reaction) and of the universe. 

Concept #4: Total Entropy & Spontaneity

If the entropy is greater than zero then we classify the process as spontaneous. 

Concept #5: The Entropy of a Reaction

The entropy, enthalpy and Gibbs Free energy of a reaction is equal to products minus reactants. 

Example #6: The oxidation of iron metal is given by the following reaction: 

Practice: Diethyl ether (C4H10O2, MW = 90.1 g/mol) has a boiling point of 35.6oC and heat of vaporization of 26.7 kJ/mol. What is the change in entropy (in kJ/K) when 3.2 g of diethyl ether at 35.6oC vaporizes at its boiling point?

Concept #6: Trouton's Rule & Boltzmann's Equation 

Additional Problems
Which of the following has the smallest molar entropy at 298 K? 1. Ne(g) 2. F2(g) 3. N2(g) 4. Cl2(g) 5. He2(g)
When an aqueous solution containing Al 3+ at 25°C is mixed with an aqueous solution of hydroxide at 25°C an immediate precipitate of insoluble aluminum hydroxide is formed: Al 3+ (aq) + 3 OH – (aq) →  Al(OH)3 (s) The standard reaction enthalpy (ΔH°) of this reaction is -61.33 kJ/mol. a) Calculate ΔS°, ΔSsurr and ΔStot for this reaction
Which of the following processes result(s) in an increase in the entropy of the system? All systems are closed systems.  
For the dissociation reaction of the acid HF HF ⇌ H+ + F - ΔS is observed to be negative. The BEST explanation for this is: A. This is the expected result since each HF molecule produces two ions when it dissociates. B. Hydration of the ions produces the negative value of ΔS. C. The reaction is expected to be exothermic and thus ΔS should be negative. D. The reaction is expected to be endothermic and thus ΔS should be negative. E. None of these can explain the negative value of ΔS.
Consider the reaction of N2O5 at 25°C for which the following data are relevant: 2 N2O5 (g) ⇌ 4 NO2 (g) + O2 (g) What is ΔS° for the reaction (in J/K)? A. 89.5 B. 249.2 C. 453.8 D. 249.2 E. -115.6 
One of the major sources of NOx compounds in our atmosphere is the reaction between nitrogen and oxygen, for example N2(g) + 2O2(g) → 2NO2(g) This reaction is not favored at normal surface temperatures, but it does occur within internal combustion engines when air is mixed with the fuel to provide oxygen for the combustion reaction.    a. Before doing any calculations, predict the sign of ΔS°. ___________________.  Explain your reasoning.   b. Now calculate ΔH° and ΔS° for the above reaction. Some thermodynamic data is provided in the table below.   c. Is there a temperature range at which the above reaction would be spontaneous? If so, give the temperature range. If not, speculate on why the reaction occurs at higher temperatures.      
Which one of the following reactions is most likely to have a positive ΔS°? a) Cu2+ (aq) + 4 Cl -  (aq) → CuCl42-(aq) b) SiH4 (g) + 2O2 (g) → SiO2 (s) + 2 H2O (g) c) SiF4 (g) + 2 H2O (g)  → SiO2 (s) + 4 HF (g) d) H2O (l)  → H2O (s) e) NO (g) + O3 (g)  → NO2 (g) + O2 (g)    
Which one of the following reactions is likely to have a ΔS° close to zero (in other words, neither positive nor negative)? a) PCl 3(g) + Cl2(g) ⇌ PCl 3(g) b) 2KClO 3(s) ⇌ 2KCl(s) + 3O 2(g) c) CO(g) + H 2O(g) ⇌ CO 2(g) + H 2(g) d) CO 2(g) ⇌ CO 2(s) e) C 5H 12(l) + 8O 2(g) ⇌ 5CO 2(g) + 6H 2O(g)     Place the following compounds in order of increasing S°: PCl5(s)          PCl 5(g)          PCl 3(g) a) PCl5(s) < PCl5(g) < PCl3(g) b) PCl5(s) < PCl3(g) < PCl5(g) c) PCl5(g) < PCl5(s) < PCl3(g) d) PCl5(g) < PCl3(g) < PCl5(s) e) PCl3(g) < PCl5(g) < PCl5(s) f) PCl3(g) < PCl5(s) < PCl5(g)      
Ce2(SO4)3 becomes less soluble in water as temperature increases because it has a negative entropy of solvation. Most other salts become more soluble in water with increasing temperature because their entropy of solvation is positive. Which explanation best describes this discrepancy? a) The bond strength of Ce2(SO4)3 is very strong, which leads to an increase in the order of the system during the reaction. b) The highly charged Ce3+ and SO42- ions become surrounded by a uniquely ordered sphere of water molecules, which increases the order of the system. c) The solid structure of Ce2(SO4)3 lacks a highly ordered crystal structure thereby leading to a decrease in the order of the system during the reaction.  d) The ions Ce3+ and SO42- repel water molecules, which leads to a decrease in the order of the system during the reaction. e) There is no explanation for this phenomenon. 
For which of these processes is the value of Δ S expected to be negative? I. Sugar is dissolved in water. II. Steam is condensed. III. CaCO3 is decomposed into CaO and CO2. a) I only b) I and III only c) II only d) II and III only
In which process is entropy decreased ? a) dissolving sugar in water b) expanding a gas c) evaporating a liquid d) freezing water
The diagram below shows the variation in entropy with temperature for a substance that is a gas at the highest temperature depicted. Accordingly, which of the following statements is not true? (a) The “zero point” is explained by the Second Law of Thermodynamics. (b) The entropy of a substance increases with temperature. (c) A solid has the least dispersed energy and the lowest entropy. (d) The vertical line 1 corresponds to ΔSfusion. (e) The increase in entropy for liquid  ⇌ gas is greater than for solid ⇌ liquid  
For which reaction, carried out at standard conditions, would both the enthalpy and entropy changes drive the reaction in the same direction? a) 2 H2 (g) + O2 (g) → 2 H2O (l)         ΔH = - 571.1 kJ b) 2 Na (s) + Cl2 (g) → 2 NaCl (s)      ΔH = - 822.0 kJ c) N2 (g) + 2 O2 (g) → 2 NO2 (g)        ΔH = + 67.7 kJ d) 2 NH3 (g) → N2 (g) + 3 H2 (g)        ΔH = + 92.4 kJ
Which of the following has the greatest entropy, S? (a) 1.00 mole of liquid water at 30° C (b) 1.00 mole of water vapor at 30° C (c) 1.00 mole of regular ice at -10° C  (d) 1.00 mole of “dry ice” (solid CO2) at -10° C (e) 1.00 mole of water under 10 atm of pressure at -10° C
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 298 K.   N2(g) + 2 O2(g) → 2 NO2(g) ΔH = +66.4 kJ   a) ΔSsurr = +223 J/K b) ΔSsurr = -223 J/K c) ΔSsurr = -66.4 J/K d) ΔSsurr = +2656 kJ/K  
Which of these species has the highest entropy (S°) at 25°C? A) CH3OH(l) B) CO(g) C) MgCO3(s) D) H2O(l) E) Ni(s)
Which responses include all of the following processes that are acccompanied by an increase in entropy? 1. I2(s) → I2(g) 2. 2I(g) → I2(g) 3. 2NH3(g) → N2(g) + 3H2(g) 4. Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s)   A) 1, 2 B) 1, 3 C) 3, 4 D) 3 E) 2, 4  
Which of the following processes would have a positive ΔSsys value? (a) He(g), 2 atm → He(g), 10 atm (b) 2 NO2(g) → N2O4(g) (c) H2(g) + I2(s) → 2 HI(g) (d) 2 Ag(s) + Br2(l) → 2 AgBr(s) (e) O2(g) → O2(aq)
Determine ΔS° for the reaction SO3(g) + H2O(l) → H2SO4(l).                  S° (J/K•mol) SO3(g)         256.2 H2O(l)         69.9 H2SO4(l)     156.9   A) 169.2   J/K•mol B) 1343.2 J/K•mol C) -169.2  J/K•mol D) -29.4    J/K•mol E) 29.4     J/K•mol
Elemental boron can be forrmed by reaction of boron trichloride with hydrogen.  BCl3(g) + 1.5H2(g) → B(s) + 3HCl(g) Substance:    BCl3(g)       H2(g)          B(s)         HCl(g) (J/K•mol):          ?            130.6         5.87      186.8   If ΔS°rxn = 80.3 J/K, what is S° for BCl3(g)? A) -18.2   J/K•mol B) 18.2    J/K•mol C) 290.1  J/K•mol D) 355.4  J/K•mol E) 450.6  J/K•mol
Identify the change in state for which there is an increase in the entropy of the system. A) water condensing B) crystallization of NaCl(s); NaCl(aq) → NaCl(s) C) compression of Air; air(1atm) → air(200 atm) D) ddry ice subliming E) water freezing
Which of the following processes is accompanied by a decrease in entropy of the system? A) C6H12O6(s) → 3CH3OH(l) + CO(g) + 2C(s) B) Ni(s) + 4CO(g) → Ni(CO)4(g) C) NaHCO3(aq) + HCl(aq) → H2O(l) + NaCl(aq) + CO2(g) D) NaClO3(s) → Na+(aq) + ClO31-(aq) E) None of the above
Calculate the normal boiling point of chloroform given that the standard entropy and enthalpy of vaporization of chloroform is +93.7 J/K/mol and 31.4 kJ/mol, respectively. 1. 215 K 2. 450 K 3. 405 K 4. 375 K 5. 335 K
Place the following in order of increasing molar entropy at 298 K. [Least (left) - Most (right)]     C(s)           O2(g)         Ne (g) A) C(s)    <   O2(g)    <   Ne (g) B) O2(g)  <   C(s)      <  Ne (g) C) Ne(g)   <  O2(g)      <  C(s) D) Ne(g)    <  C(s)        <  O2(g) E) C(s)       <  Ne(g)     <  O2(g)
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 398 K. Predice whether or not this reaction will be spontaneous at this temperature. 2 N2(g) + O2(g) → 2 NO2(g)                   ΔH = +163.2 kJ A) ΔSsurr = -548 J/K, reaction is spontaneous B) ΔSsurr = -548 J/K, reaction is not spontaneous C) ΔSsurr = -410 J/K, reaction is not spontaneous D) ΔSsurr = -410 J/K, reaction is spontaneous E) ΔSsurr = -410 J/K, it is not possible to predict the spontaneity of this reaction without more information.
Calculate ΔS°rxn for the following rreaction. The S° for each species is shown below the reaction.                          H   2      +     Cl 2(g)   →   2HCl(g) S°(J/mol•K)     130.7         223.1         186.9 A) -20 J/K B) +20 J/K C) -166.9 J/K D) +166.9 J/K E) +466.2 J/K
Identify the change in state that  DOES NOT have an increase in entropy of the system. A) water evaporating B) water boiling C) ice melting D) dry ice subliming E) water freezing
In which example does entropy increase? I. A piece of fruit freezes in liquid nitrogen. II. Librarians put library books back onto shelves at the end of the day. III. Liquid nitrogen boils in a beaker at room temperature. IV. Dry ice sublimes. V. A balloon collapses as its contents cool in liquid nitrogen. 1. I, III, IV, or V only 2. IV or V only 3. I, II, III, IV, or V 4. II only 5. IV only 6. II or III only 7. III only 8. II or IV only 9. III or IV only
Which of the following processes shows a decrease in entropy of the system? A) CH3OH(l) → CO(g) + 2H2(g) B) COCl2(g) → CO(g) + Cl2(g) C) 2 NO(g) + O2(g) → 2 NO2(g) D) NaClO3(s) → Na+(aq) + ClO3-(aq) E) None of the above will show a decrease in entropy.  
Predict which substance in each pair has the greater molar entropy: a) butane, CH3CH2CH2CH3 or 2-butene, CH 3CH=CHCH3 b) Ne (g) or Xe (g) c) CH4 (g) or CCl4 (l) d) CH3OH (l) or C 2H5OH (l) e) KClO3 (s) or KClO3 (aq) f) Na (s) or K (s)
Which of the following would probably have a positive ∆S value? 1. O2(g) → O2(aq) 2. He(g, 2 atm) → He(g, 10 atm) 3. 2 NO2(g) → N2O4(g) 4. 2 Ag(s) + Br2(l) → 2 AgBr(s) 5. H2(g) + I2(s) → 2 HI(g)
Predict the sign of ΔS for each of the following: a) A piece of wax melting b) Silver chloride precipitating from solution c) Alcohol evaporating d) A solid explosive converting to a gas e) 2 K(s) + F2 g) → 2 KF(s) f) NH3(g) + HBr(g) → NH4Br(s) g) NaClO3(s) → Na+(aq) + ClO3- (aq)
Place the following in order of increasing molar entropy at 298 K. CO2          C 3H 8             SO A) CO2 < C3H8 < SO B) C3H8 < CO2 < SO C) CO2 < SO < C3H8 D) SO < C3H8 < CO2 E) SO < CO2 < C3H8
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 398 K. Predict whether or not this reaction will be spontaneous at this temperature. 4 NH3(g) + 3 O2(g)  →  2 N2(g) + 6 H2O(g) ΔH = -1267 kJ A) ΔSsurr = +3.18 kJ/K, reaction is spontaneous B) ΔSsurr = -12.67 kJ/K, reaction is spontaneous C) ΔSsurr = +50.4 kJ/K, reaction is not spontaneous D) ΔSsurr = +12.67 kJ/K, reaction is not spontaneous E) ΔSsurr = -3.18 kJ/K, it is not possible to predict the spontaneity of this reaction without more information.  
Calculate the standard entropy of fusion of ethanol at its melting point 159 K. The standard molar enthalpy of fusion of ethanol at its melting point is 5.02 kJ · mol−1. 1. −44.0 J · K−1· mol−1 2. −5.02 kJ · K−1· mol−1 3. −31.6 J · K−1· mol−1 4. +5.02 kJ · K−1· mol−1 5. +31.6 J · K−1· mol−1
Calculate the change in the standard entropy of the system, ΔS°, for the synthesis of ammonia from N2(g) and H2(g) at 298 K.  S° (N2) = 191.5 J/mol•K S° (H2) = 130.6 J/mol•K S° (NH3) = 192.5 J/mol•K
Consider the reaction of N2O5 at 25°C for which the following data are relevant: 2 N2O5 (g) → 4 NO2 (g) + O2 (g) Substance             ΔH°f                               S°              N 2O5                    11.29 kJ/mol             355.3 J/K mol               NO 2                     33.15 kJ/mol             239.9 J/K mol               O 2                                   ?                     204.8 J/K mol   What is ΔS° for the reaction (in J/K)? a) 89.5 b) 249.2 c) 453.8 d) 249.2 e) -115.6
Calculate ΔS°rxn for the following reaction. The S° for each species is shown below the reaction. C2H2(g) + H2(g) → C2H4(g) S°(J/mol·K)              200.9             130.7               219.3 A) +112.3 J/K B) +550.9 J/K C) -550.9 J/K D) +337.1 J/K E) -112.3 J/K    
A system releases 900 J of heat to the surroundings, which are at a constant 27 ◦C. What is ∆S of the surroundings? 1. 33.3 J · K−1 2. −3 J · K−1 3. 3 J · K−1 4. −33.3 J · K−1
HI has a boiling point of –35.4 oC with a standard enthalpy of vaporization of 21.16 kJ/mol. Calculate the standard entropy of vaporization of HI. a) 598 J/K·mol b) 68.6 J/K·mol c) 75.2 J/K·mol d) 0.068 J/K·mol e) 89.0 J/K·mol
Which of the following reaction(s) is/are predicted to have favorable ∆S ̊rxn? a) N2 (g) + 3 H2 (g) → 2 NH3 (g) b) H2O (l) → H2O (s) c) C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) d) Both a and b e) None of the above
Benzene has a ΔHvap = 33.90 kJ/mol and a ΔSvap = 96.4 J/mol-K. What is the vaporization temperature of Benzene in Celsius? A. −273 B. 78.5 C. 352 D. 2570 E. 2840
The compound benzoic acid, C6H5COOH, melts at 122.4 ̊C. If the enthalpy of fusion of this compound is 17.3 kJ/mol, what is its entropy of fusion? a. 31.3 J/mol·K b. 34.1 J/mol·K c. 38.0 J/mol·K d. 40.2 J/mol·K e. 43.8 J/mol·K
Consider the following figure of four processes from the initial state. The substances are in gas phase initially. Which process(es) would result in an entropy increase?   A. (1) and (2)  B. (1) and (3) C. only (3) D. (1), (2), and (4) E. only (4)  
Balance the following reaction and then solve for the ∆S (J/K-mol) for this reaction. Li (g) + H2(g) → LiH (s) With S° (J/K-mol) value of LiH = 20.0          Li = 138.7        H   2 = 130.6 A. −368.0 B. −249.3 C. −106.8 D. 249.3 E. 368.0  
  Explain the following plot:
Of the following descriptions, how many (the total number) would increase entropy? Sublimation of sodium; C2H6 (g) → C2H2 (g) + 2 H2(g); Heating hexane; Boiling water A.none of them B. 1 C. 2 D. 3 E. All of them
Consider the following processes (Treat all gases as ideal). 1. Nitrogen gas is compressed isothermally to one half its original volume. 2. Carbon dioxide is allowed to expand isothermally to 10 times its original volume. 3. A glass of water loses 100 J of energy reversibly at 30°C. 4. The temperature of one mole of helium is increased 25°C at constant pressure. 5. The pressure of one mole of oxygen gas is allowed to double isothermally.   Which of these processes leads to an increase in entropy?   a) 1 and 4         b) 5         c) 3 and 5         d) 2 and 4         e) 1 and 2  
For which process is the entropy change per mole the largest at constant temperature?  (A) H2O(l) → H2O(g) (B) H2O(s) → H2O(g) (C) H2O(s) → H2O(l) (D) H2O(l) → H2O(s)
Which of the following processes have a positive entropy term?   A. Synthesis of ammonia from nitrogen and hydrogen gas. B. Creation of sodium bicarbonate from gaseous water, carbon dioxide and sodium carbonate C. Freezing of methanol D. Creation of carbon monoxide and hydrogen gas from gaseous methane and gaseous water E. All of the above have a positive entropy term. 
Which of the following would have the   highest value of absolute entropy per mole? a) Water at 50 oC b) Water at 10 oC c) Ice at -10 oC d) 1 M NaCl at 50 oC e) 1 M NaCl at 10 oC  
Which of the following statements describes situations where entropy increases: I. Increase in number of gas particles present II. Separated gas particles in a flask being allowed to mix III. Gas particles undergo deposition   A. Only I                 B. Only II                 C. Only III               D. I and II               E. All three
Would you expect the entropy of the system to  increase or decrease for each of the following processes: a. CaCO3 (s) → CaO (s) + CO2 (g)       ________________   b. H2O (g) → H2O (l)                             ________________
When temperature is increased and pressure is held fixed across a phase change which of the following statements is true? A. Entropy is negative and enthalpy is positive. B. Entropy is negative and enthalpy is negative. C. Entropy is positive and enthalpy is positive. D. Entropy is positive and enthalpy is negative.
Coal is a major source of energy that can be converted from its solid, raw form to a gaseous phase of fuel. This is accomplished by the water gas reaction: C (s) + H2O (g)      →      CO (g) + H2 (g) What is the entropy value for the water gas reaction shown above?   A. – 268 kJ/mol B. – 134 kJ/mol C. 0 kJ/mol D. +134 kJ/mol
Which of the following reactions would be entropically favored?   A) Precipitation of ions from a supersaturated solution. B) Deposition of gaseous carbon dioxide. C) Ionization of an organic compound. D) The fusion of inorganic nuclides. 
Arrange the following substances in the order of increasing entropy at 25° C.               CO 2 (s)         Kr (g)         S  8 (s)         O 3 (g)         H 2O (l)         H 2S (l)
Which of the following statements describes situations where entropy increases: I.  Increase in number of gas particles present II.  Separated gas particles in a flask being allowed to mix III.  Gas particles undergo deposition   A.  Only I                  B.  Only II                  C.  Only III                   D.  I and II                  E.  All three
Consider the following processes (at 298 K) given below and determine for which is ΔS positive?
Consider the following reaction at constant pressure. Use the information here to determine the value of ∆Ssurr at room temperature. Predict whether or not this reaction will be spontaneous at this temperature. N2 (g) + 2 O2 (g) → 2 NO2 (g)              ∆H° = + 66.4 kJ ∆Ssurr = - 223J/K, not spontaneous ∆Ssurr = + 265 J/K, not spontaneous ∆Ssurr = + 223 J/K, is spontaneous ∆Ssurr = - 66.4 J/K, not spontaneous ∆Ssurr = - 66.4 J/K, not possible to predict the spontaneity 
Predict the sign on ΔS° for the following reactions i. 2 KClO4 (s) → 2 KClO3(s) + O2(g) ii. Propanol condenses at room temperature iii. CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)            Reaction i          Reaction ii          Reaction iii A.          +                            +                           - B.           -                             +                          + C.           +                             -                          0  D.            -                            +                          0 E.            +                            -                          -   
Rank the standard molar entropy of the following from lowest to highest. 1. H2O2 (l) 2. H2O (g) 3. H2O (l) 4. H2O2 (aq) a) 4 < 1 < 3 < 2     b) 1 < 3 < 4 < 2 c) 3 < 1 < 4 < 2 d) 2 < 4 < 3 < 1 e) 1 < 3 < 2 < 4 
Would you expect the entropy of the system to  increase or decrease for each of the following processes: a. N2 (g) + 3H2 (g) → 2NH3 (g)       ________________   b. H2O (l) → H2O (g)                        ________________
When most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here: Suppose you stretch a rubber band.Do you expect the entropy of the system to increase or decrease?
Predict the sign of the entropy change of the system for each of the following reactions.(a) N2 (g) + 3H2 (g)  →  2NH3 (g) (b) CaCO3(s)  →  CaO(s) + CO2(g) (c) 3C2H2(g)  →  C6H6(g) (d) Al2O3(s) + 3H2 (g)  →  2Al(s) + 3H2O(g)
The accompanying diagram shows how the free energy, G, changes during a hypothetical reaction A(g) +B(g) →  C(g). On the left are pure reactants A and B, each at 1 atm, and on the right is the pure product, C, also at 1 atm. Indicate whether each of the following statements is true or false. The entropy change for this reaction is positive.
In chemical kinetics, the entropy of activation is the entropy change for the process in which the reactants reach the activated complex.Predict whether the entropy of activation for a bimolecular process is usually positive or negative.
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.Sc(s) and Sc(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.NH3(g) and NH3(aq)
Which process has the larger entropy change: melting ice or boiling water?
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.1 mol O2(g) and 2 mol O3(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.C (graphite) and C (diamond)
In each of the following pairs, which compound would you expect to have the higher standard molar entropy?C2 H2 (g) or C2 H6 (g);
In each of the following pairs, which compound would you expect to have the higher standard molar entropy?CO2 (g) or CO(g).
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.He(l) or He(g).
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.1 mol of Ne(g) in 16.0 L or 1 mol of Ne(g) in 1.60 L.
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.CO2(g) or CO2(s).
Why does the entropy of a gas increase when it expands into a vacuum?
What happens to the entropy of a sample of matter when it changes state from a solid to a liquid?
How does the standard entropy of a substance depend on its molar mass?
How does the standard entropy of a substance depend on its molecular complexity?
How does the entropy of the system change when a solid melts, a gas liquefies, a solid sublimes?
Entropy increases with increasing temperature.Why does the plot show vertical jumps at the melting and boiling points?
How does the molar entropy of a substance change with increasing temperature?
Methanol (CH3OH) can be made by the controlled oxidation of methane: CH4(g) + O2(g)  →  CH3OH(g)Use data in Appendix C in the textbook to calculate S S for this reaction.
How can you calculate the standard entropy change for a reaction from tables of standard entropies?
If energy can flow in and out of the system to maintain a constant temperature during the process, what can you say about the entropy change of the surroundings as a result of this process?
True or false: An endothermic process increases the entropy of the surroundings. ________
Predict how the entropy of the substance is affected in the following processes. CH4(g, 125°c) → CH4(g, 200°C)  a) increases b) decreases c) remains the same
For the following questions circle the correct answer. There is one and only one correct answer. The substance with the largest value for entropy (at T = 25.0 °C and p = 1.00 atm). a) CH3CH2CN(l) b) CH3CN(I) c) CH3CH2CN(g) d) CH3CN(g)
Why does the solubility of NaCl only increase slowly with water temperature?A. ΔSsol > 0 but small in magnitudeB. ΔSsol < 0 but small in magnitudeC. ΔHsol > 0 but small in magnitudeD. ΔHsol < 0 but small in magnitudeE. it has a very large lattice energy
Consider the following reaction at 298 K2Al (s) + 3Cl2 (g) → 2AlCl3 (s)         H=-1408 KJCalculate the following quantities:(a) Ssys= ? (b) Ssurr= ?(c) Suniv= ?
Using the following data, calculate ΔSfus and ΔSvap for HBr.Determine the entropy change when 4.80 mol of HBr (f) freezes at atmospheric pressure. 
Which of the following species has the highest entropy (S°) at 25°C?A. MgCO3(s)B. CO(g)C. H2O(l) D. CO2(g)E. CH3OH(l)
CO(NH2)2(aq) + H2O(l) → CO2(g) +2NH3(g) ΔS° = +354.8 J/mol*KGiven the data below, calculate the ΔS° f for UreaSubstance S° (J/molK)H2O (l) 69.96CO2 (g) 213.6NH3 (g) 192.5 
Which of the following reactions have a positive ΔS rxn?  a) 2 A(g) + B(s) → 3 C(g) b) 2 A(g) + B(g) → C(g) c) A(g) + B(g) → C(g) d) 2 A(g) + 2 B(g) → 5 C(g) e) More than one of the above
ΔS is positive for the reaction _________________.a. 2NO(g) + O 2(g) → 2NO2(g)b. 2N2(g) + 2H2(g) → 2NH3(g)c. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) d. Mg(s) + Cl2(g) → MgCl2(s)e. C2H4(g) + H2(g) → C2H6(g)
HI has a normal boiling point of -35.4°C, and its ΔHvap is 21.16kJ/mol. Calculate the molar entropy of vaporization (ΔSvap).A. 68.6 J/K • molB. 0.068 J/K • molC. 598 J/K • molD. 89.0 J/K • molE. 75.2 J/K • mol
The enthalpy of vaporization of acetone is 31.3 kJ/mol, and its boiling point is 56.3°C. What is the entropy change for the vaporization (boiling) of acetone?
The ΔH°vap for pure water is 40.65 kJ/mol. Calculate the ΔS°vap for pure water.
The enthalpy of vaporization of methanol is 35.27 kJ mol-1 at its boiling point of 64.1°Ca. Calculate the entropy of vaporization of methanol at this temperature.b. Calculate the entropy of surroundings.
Which of the following statements describes situations where entropy increases:                                     I.  Increase in number of gas particles present                                     II.  Separated gas particles in a flask being allowed to mix                                     III.  Gas particles undergo deposition   A.  Only I              B.  Only II        C.  Only III        D.  I and II       E.  All three
Predict the sign of the entropy change, ΔS°, for each of the reaction displayed.i) 2NO2 (g) → N2 (g) + 2O2 (g)ii) C5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (g)iii) 2NaClO3 (s) → 2NaCl (s) + 3O2 (g)iv) 2Na (s) + Cl2 (g) → 2NaCl (s)v) CH3OH (l) → CH3OH (g)
HI has a boiling point of –35.4°C with a standard enthalpy of vaporization of 21.16 kJ/mol. Calculate the standard entropy of vaporization of HI.a) 598 J/K·molb) 68.6 J/K·molc) 75.2 J/K·mold) 0.068 J/K·mole) 89.0 J/K·mol
Which of the following reactions have a positive delta S rxn? Check all that apply.
How many of the following processes represent an increase in entropy:* Water is heated in the microwave from 23 Celsius to 90 Celsius* The sublimation of I2* CO 2 gas is dissolved in water to make a carbonated beverage* N2O4 (g) → 2 NO2 (g)A. noneB. oneC. twoD. threeE. all four
The thermodynamic quantity that expresses the degree of disorder in a system is _________. a. enthalpy b. internal energy c. bond energy d. entropy e. heat flow
Which one of the following processes produces a decrease in the entropy of the system? a. boiling water to form steam b. dissolution of solid KCl in water c. mixing of two gases into one container d. freezing water to form ice e. melting ice to form water 
ΔS is positive for the reaction _______. a. CaO(s) + CO2(g) → CaCO3(s) b. N2(g) + 3H2(g) → 2NH3(g) c. 2SO3(g) → 2SO2(g) + O2(g) d. Ag+(aq) + Cl-(aq)→AgCl(s) e. H2O(l) → H2O(s)   
For one mole of substance at a given temperature, select the member in each pair with the higher entropy.a. P2(g), P4(g)b. CaF2(s), BaCl2(s)c. CuSO4(s), CuSO4•5H2O(s)
Which of the following reaction(s) is/are predicted to have favorable ∆S°rxn? a) N2 (g) + 3 H2 (g) → 2 NH3 (g) b) H2O (l) → H2O (s) c) C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) d) Both a and b e) None of the above
Nitric oxides, NO and NO2, contribute to air pollution, acid rain, and the depletion of the ozone layer. After NO forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form NO2. The reaction is given by 2NO(g) + O2(g) → 2NO2(g) Calculate ΔSrxn∘ for the reaction.
Which of the following phase changes is correctly paired with the sign of its change in entropy and its change in enthalpy?
What are the signs for the change in enthalpy and change in entropy when a system undergoes the phase transition of freezing?A. ∆H < 0 , ∆S < 0B. ∆H > 0 , ∆S > 0C. ∆H < 0 , ∆S > 0D. ∆H > 0 , ∆S < 0
Which of the following processes involves a decrease in entropy? a. the decomposition of NH 3 (g) b. the condensation of steam c. the sublimation of CO2  d. the evaporation of ethanol e. the dissolution of NH4NO3(s) in water f.  I2 at 90oC and 5.0 atm  →  I2 at 50oC and 10.0 atm g. NH4Cl(s) → HCl(g) +  NH3(g) h. CH4(g)  +  2 O2(g)  →  CO2(g)  +  2 H2O(l) 
Which reaction is/are predicted to have a negative entropy of reaction? a) CH3CH2OH (s) → CH3CH2OH (l) b) CH3CH2OH (l, 10 ̊C) → CH3CH2OH (l, 50 ̊C) c) CH3CH2OH (l, 50 ̊C) → CH3CH2OH (l, 10 ̊C) d) Both a and b e) Both a and c
Predict how the entropy of the substance is affected in the following process:                                           Ar(l) → Ar(g) a) increasesb) decreases 
Calculate ΔS∘rxn for this balanced chemical equation.2NO(g) + O2(g) → 2NO2(g)Express your answer to one decimal place and include the appropriate units.
Given the standard entropy values in the table below, determine the standard entropy change of the reaction below that produces 10.0 g of metallic Cu. 
Predict how the entropy of the substance is affected in the following process? Br2 (l, 1 bar, 25°celcius) yields Br2 (g, 1 bar, 25°Celsius) a) Increases b) decreases c) stays the same
Using the data in the table, calculate the standard entropy changes for the following reactions at 25°.
Given the values of ΔH∘rxn, ΔS∘rxn, and T below, determine ΔSuniv. a. ΔH∘rxn = 84 kJ , ΔS∘rxn = 144 J/K , T = 303 K b. ΔH∘rxn = 84 kJ , ΔS∘rxn = 144 J/K , T = 762 K c. ΔH∘rxn = 84 kJ , ΔS∘rxn = −144 J/K , T = 303 K d. ΔH∘rxn = − 84 kJ , ΔS∘rxn = 144 J/K , T = 406 K
Determine the sign of ΔSsys in each of the following processes: Water boiling
Determine the sign of ΔSsys in each of the following processes: Water freezing
Determine the sign of ΔSsys in each of the following processes:
Determine the sign of ΔSsys in each of the following processes: dry ice subliming
Determine the sign of ΔSsys in each of the following processes: dew forming
Determine the sign of ΔSsys in each of the following processes:
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions.a. Mg(s) + Cl2(g) → MgCl2(s)b. 2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g)c. 2 O3(g) → 3 O2(g)d. HCl(g) + NH3(g) → NH4Cl(s)
Consider two processes: sublimation of I2 (s) and melting of I2 (s) (Note: the latter process can occur at the same temperature but somewhat higher pressure).I2(s) ⟶ I2(g)                    I 2(s) ⟶ I2(l)Is ΔS  positive or negative in these processes? In which of the processes will the magnitude of the entropy change be greater?
Predict the sign of the entropy change for the following process: An ice cube is warmed to near its melting point.
Predict the sign of the entropy change for the following process: Exhaled breath forms fog on a cold morning.
Predict the sign of the entropy change for the following process: Snow melts.
Predict the sign of the entropy change for the following process. Give a reason for your prediction.Pb2+(aq) + S2−(aq) ⟶ PbS(s)
Predict the sign of the entropy change for the following process. Give a reason for your prediction.2 Fe(s) + 3/2 O2(g) ⟶ Fe2O2(s)
Predict the sign of the entropy change for the following process. Give a reason for your prediction.2 C6H14(l) + 19 O2(g) ⟶ 14 H2O(g) + 12 CO2(g)
Write the balanced chemical equation for the combustion of methane, CH4(g), to give carbon dioxide and water vapor. Explain why it is difficult to predict whether ΔS is positive or negative for this chemical reaction.
Write the balanced chemical equation for the combustion of benzene, C6H6(l), to give carbon dioxide and water vapor. Would you expect ΔS to be positive or negative in this process?
Predict the sign of ΔS surr for the following process.a. H2O(l) → H2O(g)
Predict the sign of ΔS surr for the following process.b. I2(g) → I2(s)
Predict the sign of ΔS sys for the process: (a) A piece of wax melts.
Predict the sign of ΔS sys for the process: (b) Silver chloride precipitates from solution.
Predict the sign of ΔS sys for the process: (c) Dew forms on a lawn in the morning.
Predict the sign of ΔS sys for the process: (a) Gasoline vapors mix with air in a car engine.
Predict the sign of ΔS sys for the process: (b) Hot air expands.
Predict the sign of ΔS sys for the process: (c) Humidity condenses in cold air.
Predict the sign of ΔS sys for the process: (a) Alcohol evaporates.
Predict the sign of ΔS sys for the process: (b) A solid explosive converts to a gas.
Predict the sign of ΔS sys for the process: (c) Perfume vapors diffuse through a room.
Predict the sign of ΔSsys for the following process:(a) A pond freezes in winter.
Predict the sign of ΔSsys for the following process:(b) Atmospheric CO2 dissolves in the ocean.
Predict the sign of ΔSsys for the following process:(c) An apple tree bears fruit.
Without using Appendix B, predict the sign of ΔS° for 2K(s) + F 2(g) ⟶ 2KF(s)
Predict the sign of sys for each of the following processes.
Without using Appendix B, predict the sign of ΔS° for NH 3(g) + HBr(g) ⟶ NH 4Br(s)
Without using Appendix B, predict the sign of ΔS° for NaClO 3(s) ⟶ Na+(aq) + ClO3−(aq)
Predict the sign of ΔS for each process.(a) the boiling of water(b) I2(g) → I2(s)(c) CaCO3(s)→ CaO(s) + CO2(g)
Without using Appendix B, predict the sign of ΔS° for H 2S(g) + 1/2O2(g) ⟶ 1/8S8(s) + H2O(g)
Without using Appendix B, predict the sign of ΔS° for HCl( aq) + NaOH(aq) ⟶ NaCl(aq) + H2O(l)
Which of the following processes have a ΔS > 0? a. 2NH3(g) + CO2(g) → NH2CONH2(aq) + H2O(l) b. lithium fluoride forms from its elements c. 2HF(g) → H2(g) + F2(l) d. potassium iodide dissolves in pure water
Without using Appendix B, predict the sign of ΔS° for 2NO 2(g) ⟶ N2O4(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Without using Appendix B, predict the sign of ΔS° for CaCO 3(s) + 2HCl(aq) ⟶ CaCl2(aq) + H2O(l) + CO2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Without using Appendix B, predict the sign of ΔS° for 2NO(g) + O 2(g) ⟶ 2NO2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Consider these three changes in the possible distributions of six gaseous particles within three interconnected boxes. Which change has a positive ΔS?
Without using Appendix B, predict the sign of ΔS° for 2KClO 3(s) ⟶ 2KCl(s) + 3O2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Which of the following reactions (or processes) are expected to have a negative value for ΔS°?a. SiF6(aq) + H2(g) → 2HF(g) + SiF4(g)b. 4Al(s) + 3O 2(g) → 2Al2O3(s)c. CO(g) + Cl 2(g) → COCl2(g)d. C2H4(g) + H2O(l) → C2H5OH(l)e. H2O(s) → H2O(l)
Predict the sign of ΔS° for each of the following changes. a. K (s) + 1/2Br2 (g) → KBr (s)
Predict the sign of ΔS° for each of the following changes. b. N2 (g) + 3H2 (g) → 2NH3 (g)
Predict the sign of ΔS° for each of the following changes. c. KBr (s) → K+ (aq) + Br - (aq)
Which reaction is most likely to have a positive ΔSsys?a) SiO2(s) + 3 C(s) → SiC(s) + 2 CO(g)b) 6 CO2(g) + 6 H2O(g) → C6H12O6(s) + 6 O2(g)c) CO(g) + Cl2(g) → COCl2(g)d) 3 NO2(g) + H2O(l) → 2 HNO3(l) + NO(g)
Predict the sign of ΔS° for each of the following changes. d. KBr (s) → KBr (l)
Without using Appendix B, predict the sign of ΔS° for Ag +(aq) + Cl −(aq) ⟶ AgCl(s)
Without using Appendix B, predict the sign of ΔS° for KBr(s) ⟶ KBr(aq)
Without using Appendix B, predict the sign of ΔS° for the following:
Predict the sign of ΔS for the process: C 2H5OH(g) (350 K and 500 torr) ⟶ C2H5OH(g) (350 K and 250 torr)
Predict the sign of ΔS for the process: N 2(g) (298 K and 1 atm) ⟶ N2(aq) (298 K and 1 atm)
Predict the sign of ΔS for the process: O 2(aq) (303 K and 1 atm) ⟶ O 2(g) (303 K and 1 atm)
When heated, the DNA double helix separates into two random coil single strands. When cooled, the random coils reform the double helix: double helix ⇌ 2 random coils.(a) What is the sign of ΔS for the forward process? Why?
Predict the sign of ΔS for the process: O 2(g) (1.0 L at 1 atm) ⟶ O 2(g) (0.10 L at 10 atm)
Predict the sign of ΔS for the process: Cu(s) (350°C and 2.5 atm) ⟶ Cu(s) (450°C and 2.5 atm)
Predict the sign of ΔS for the process: Cl 2(g) (100°C and 1 atm) ⟶ Cl 2(g) (10°C and 1 atm)
Predict the sign of S accompanying reaction on the figure.
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions:2 KClO3(s) → 2 KCl(s) + 3 O2(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions:CH2=CH2(g) + H2(g) → CH3CH3(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions: Na(s) + 1/2 Cl2(g) → NaCl(s)
Does the entropy of the system increase, decrease, or stay the same for each of the following conditions.
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions: N2(g) + 3 H2(g) → 2 NH3(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions.a. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), ΔH˚rxn = –2044 kJb. N2(g) + O2(g) → 2 NO(g), ΔH˚rxn = +182.6 kJc. 2 N2(g) + O2(g) → 2 N2O(g), ΔH˚rxn  = +163.2 kJd. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g), ΔH˚rxn = –906 kJ
Without doing any calculations, determine the sign of ΔSsurr for each of the following chemical reactions.a. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), ΔH˚rxn = –2044 kJb. N2(g) + O2(g) → 2 NO(g), ΔH˚rxn = +182.6 kJc. 2 N2(g) + O2(g) → 2 N2O(g), ΔH˚rxn  = +163.2 kJd. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g), ΔH˚rxn = –906 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 CO(g) + O2(g) ⇌ 2 CO2(g), ΔH˚rxn = –566.0  kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 NO2(g) → 2 NO(g) + O2(g), ΔH˚rxn = +113.1 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 H2(g) + O2(g) → 2 H2O(g), ΔH˚rxn = –483.6 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.CO2(g) → C(s) + O2(g), ΔH˚rxn = +393.5 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 CO(g) + O2(g) → 2 CO2(g), ΔH˚rxn = –556.0 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 NO2(g) → 2 NO(g) + O2(g), ΔH˚rxn = +113.1 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 H2(g) + O2(g) → 2 H2O(g), ΔH˚rxn = –483.6 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.CO2(g) → C(s) + O2(g), ΔH˚rxn = +393.5 kJ
Which process will decrease entropy? a. SO2(l) → SO2(g) b. H2O(g) → H2O(l) c. CaCO3(s) → CaO(s) + CO2(g) d. 2Cl2O(g) → 2Cl2(g) + O2(g)
Given the values of ΔH∘rxn, ΔS∘rxn, and T below, determine ΔSuniv. a) ΔH∘rxn = 87 kJ , ΔS∘rxn = 146 J/K , T= 296 K, will this be spontaneous or not spontaneous? b) ΔH∘rxn = 87 kJ , ΔS∘rxn = 146 J/K , T= 762 K, will this be spontaeous or not spontaneous? c) ΔH∘rxn = 87 kJ , ΔS∘rxn = −46 J/K , T= 296 K, will this be spontaneous or not spontaneous? d) ΔH∘rxn = −87 kJ , ΔS∘rxn = 146 J/K , T= 390 K, will this be spontaneous or not spontaneous?
Entropy is a measure of a. free energy b. the heat of a reaction c. molecular randomness d. the rate of a reaction
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.PCl3(g); PCl5(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH3CH2CH2CH3(g); SO2(g)
Rank the contents of the following containers in order of decreasing entropy.
Rank the following substances in order of decreasing standard molar entropy (S˚).a. I2(g); F2(g); Br2(g); Cl2(g)b. H2O(g); H2O2(g); H2S(g)c. C(s, graphite); C(s, diamond); C(s, amorphous)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.H2(g), HBrO4(g), HBr(g)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.H2O(l), H2O(g), H2O(s)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.He(g), Cl2(g), P4(g)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.C2H5OH(l) or C3H7OH(l)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.C2H5OH(l) or C2H5OH(g)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.2 H(g) or H(g)
Which of the following involve an increase in the entropy of the system?a. melting of a solidb. sublimationc. freezingd. mixinge. separationf. boiling
Arrange these gases in order of decreasing standard molar entropy: Rank from largest to smallest. Cl2 SO3 Kr
Arrange these gases in order of decreasing standard molar entropy: SO3, Kr, Cl2.
For each of the following pairs of substances, which substance has the greater value of S°?a. Cgraphite(s) or Cdiamond(s)
Arrange the gases – F2, Ar, and CH3F – in order of increasing standard entropy (S˚) at 298 K.
For each of the following pairs of substances, which substance has the greater value of S°?b. C2H5OH (l) or C2H5OH (g)
For each of the following pairs of substances, which substance has the greater value of S°?c. CO2 (s) or CO2 (g)
For each of the following pairs, which substance has the greater value of S?a. N2O (at 0 K) or He (at 10 K)
For each of the following pairs, which substance has the greater value of S?b. N2O(g) (at 1 atm, 25°C) or He(g) (at 1 atm, 25°C)
For each of the following pairs, which substance has the greater value of S?c. NH3 (s) (at 196 K) → NH3 (l) (at 196 K)
Predict which substance has greater molar entropy. Explain.(a) Butane CH3CH2CH2CH3(g) or 2-butene CH3CH=CHCH3(g)(b) Ne(g) or Xe(g)(c) CH4(g) or CCl4(l)
Predict which substance has greater molar entropy. Explain.(a) NO2(g) or N2O4(g)(b) CH3OCH3(l) or CH3CH2OH(l)(c) HCl(g) or HBr(g)
Predict which substance has greater molar entropy. Explain.(a) CH3OH(l) or C2H5OH(l)(b) KClO3(s) or KClO3(aq)(c) Na(s) or K(s)
Predict which substance has greater molar entropy. Explain.(a) P4(g) or P2(g)(b) HNO3(aq) or HNO3(l)(c) CuSO4(s) or CuSO4·5H2O(s)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Graphite, diamond, charcoal
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) Ice, water vapor, liquid water
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) O2, O3, O atoms
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Glucose (C6H12O6), sucrose (C12H22O11), ribose (C5H10O5)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) CaCO3, Ca + C + 3/2O2, CaO + CO 2
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) SF6(g), SF4(g), S2F10(g)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) ClO4−(aq), ClO2−(aq), ClO3−(aq)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) NO2(g), NO(g), N2(g)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) Fe2O3(s), Al2O3(s), Fe3O4(s)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Mg metal, Ca metal, Ba metal
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) Hexane (C6H14), benzene (C6H6), cyclohexane (C6H12)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) PF2Cl3(g), PF5(g), PF3(g)
Kyanite, sillimanite, and andalusite all have the formula Al 2SiO5. Each is stable under different conditions (see the graph below). At the point where the three phases intersect:(c) Which mineral, if any, has the highest entropy?
Rank each of the following in order of decreasing standard molar entropy (S˚).a. NH3(g); Ne(g); SO2(g); CH3CH2OH(g); He(g)b. H2O(s); H2O(l); H2O(g)c. CH4(g); CF4(g); CCl4(g)
Rank these systems in order of decreasing entropy. Rank from highest to lowest entropy. To rank items as equivalent, overlap them. A) 1 mol carbon tetrafluoride gas at 273k 40L B) 1 mol krypton gas at 273K 40L C) 1/2 mol krypton gas at 100k 20L D) 1 mol krypton gas at 273K 20L E) 1/2 mol krypton liquid at 100K F) 1 mol fluorine gas 273 K 40L G) 1/2 mol krypton gas at 273K 20L
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CO(g); CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH3OH(l); CH3OH(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Ar(g); CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH4(g); SiH4(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CO2(g);  CH3CH2CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.NaBr(s); NaBr(aq)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.C6H6(l) and C6H6(g);
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CO(g); CO2(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance. CO(g) and CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH3OH(l); CH3OH(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.1 mol N2O4(g) and 2 mol NO2(g);
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Ar(g); CO2(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance. HCl(g) and HCl(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH4(g); SiH4(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NO2(g); CH3CH2CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NaBr(s); NaBr(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.NaNO3(s); NaNO3 (aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH4(g); CH3CH3(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 1 mol of O2(g)  at 300 oC, 0.01 atm and 1 mol of O3(g) at 300 oC, 0.01 atm.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Br2(l); Br2(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 1 mol of H2O(g) at 100 oC, 1 atm and 1 mol of H2O(l) at 100 oC, 1 atm.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Br2(g); F2(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 0.5 mol of N2(g)  at 298 K, 20-L volume and 0.5 CH4(g)  at 298 K, 20-L volume.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.PCl3(g); PCl5(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 100 g Na2SO4(s) at 30 oC and 100 g Na2SO4(aq) at 30 oC.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH3CH2CH2CH3(g); SO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NaNO3(s); NaNO3(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH4(g); CH3CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Br2(l); Br2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Br2(g); F2(g)
Calculate ΔSfus and ΔSvap for Na.
At room temperature, the entropy of the halogens increases from I2 to Br2 to Cl2. Explain.
The diagram shows the variation in entropy with temperature for a substance that is a gas at the highest temperature shown.What processes correspond to the entropy increases along the vertical lines labeled 1 and 2 in this diagram?
The diagram shows the variation in entropy with temperature for a substance that is a gas at the highest temperature shown.Why is the entropy change for process 2 larger than that for process 1?
A reaction that occur in the internal combustion engine isN2(g) + O2(g) ⥫⥬ 2NO(g)(a) Determine ΔH° and ΔS° for the reaction at 298 K.
Ethene (C2H4) can be halogenated by the following reaction: C2H4(g) + X2(g) ⇌ C2H4X2(g), where X2 can be Cl2, Br2, or I2.Use the thermodynamic data given below to calculate ΔS˚ for the halogenation reaction by Cl2 at 26 ˚C.CompoundΔH˚f (J/mol K)ΔS˚f (J/mol K)C2H4Cl2(g)–129.7308.0C2H4Br2(g)38.3330.6C2H4I2(g)66.5347.8
Ethene (C2H4) can be halogenated by the following reaction: C2H4(g) + X2(g) ⇌ C2H4X2(g), where X2 can be Cl2, Br2, or I2.Use the thermodynamic data given below to calculate ΔS˚ for the halogenation reaction by Br2 at 26 ˚C.CompoundΔH˚f (J/mol K)ΔS˚f (J/mol K)C2H4Cl2(g)–129.7308.0C2H4Br2(g)38.3330.6C2H4I2(g)66.5347.8
Calculate ΔS°298 for the following change.(a) SnCl4(l) ⟶ SnCl4(g)
Calculate ΔS°298 for the following change.(c) Cu(s) ⟶ Cu(g)
Determine the entropy change for the combustion of liquid ethanol, C 2H5OH, under the standard conditions to give gaseous carbon dioxide and liquid water.
Determine the entropy change for the combustion of gaseous propane, C 3H8, under the standard conditions to give gaseous carbon dioxide and water.
Using the relevant S°298 values listed in Appendix G, calculate ΔS°298 for the following change:(a) N2(g) + 3H2(g) ⟶ 2NH3(g)
Using the relevant S°298 values listed in Appendix G, calculate ΔS°298 for the following change:(b) N2(g) + 5/2O2(g) ⟶ N2O5(g)
From the following information, determine ΔS°298 for the following:N(g) + O(g)⟶NO(g)                ΔS° 298 = ?N2(g) + O2(g)⟶2NO(g)          ΔS° 298 = 24.8 J/KN2(g)⟶2N(g)                           ΔS°  298 = 115.0 J/KO2(g)⟶2O(g)                          ΔS°  298 = 117.0 J/K
Use the standard entropy data in Appendix G to determine the change in entropy for each of the reactions listed below. All the processes occur at the standard conditions and 25 °C.(a) MnO2(s) ⟶ Mn(s) + O2(g)(b) H2(g) + Br2(l) ⟶ 2HBr(g)(c) Cu(s) + S(g) ⟶ CuS(s)(d) 2LiOH(s) + CO2(g) ⟶ Li2CO3(s) + H2O(g)(e) CH4(g) + O2(g) ⟶ C(s, graphite) + 2H 2O(g)(f) CS2(g) + 3Cl2(g) ⟶ CCl4(g) + S2Cl2(g)
In photosynthesis, plants form glucose (C6H12O6) and oxygen from carbon dioxide and water. Calculate ΔS˚rxn at 15 ˚C{ m ^circ~ m C}.
Consider the following reaction:   2NOBr(g) ⥫⥬ 2NO(g) + Br 2(g)      K = 0.42 at 373 KGiven that S° of NOBr(g) = 272.6 J/mol·K and that ΔS°rxn and ΔH°rxn are constant with temperature, find(a) ΔS°rxn at 298 K 
Calculate ΔS˚rxn for the balanced chemical equation2 H2S(g) + 3 O2(g)  →  2 H2O(g) + 2 SO2(g)Standard enthalpies for selected substances at 25oC SubstanceΔS˚ (J/(mol•K))O2(g)205.2SO2(g)248.2SO3(g)256.8H2O(g)188.8H2S(g)205.8
Use standard entropies to calculate ΔS˚rxn for the balanced chemical equation: 2 PCl3(l) + O2(g) →  2 POCl3(l)SubstanceΔS˚ (J/mol•K)POCl3(l)222.5POCl3(g)325.5PCl3(l)217.1PCl3(g)311.8O2(g)205.2
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.b. 2SO3 (g) → 2SO2 (g) + O2 (g)
For the reactionCS2 (g) + 3O2 (g) → CO2 (g) + 2SO2 (g)ΔS° is equal to -143 J/K. Use this value and data from Appendix 4 to calculate the value of S° for CS2(g).
For the following reaction, predict the sign and find the value of ΔS°rxn:(a) 3NO2(g) + H2O(l) ⟶ 2HNO3(l) + NO(g)
For the following reaction, predict the sign and find the value of ΔS°rxn:(c) C6H12O6(s) + 6O2(g) ⟶ 6CO2(g) + 6H2O(g)
Find ΔS°rxn for the combustion of ethane (C2H6) to carbon dioxide and gaseous water. Is the sign of ΔS°rxn as expected?
Find ΔS°rxn for the combustion of ammonia to nitrogen dioxide and water vapor. Is the sign of ΔS°rxn as expected?
Find ΔS°rxn for the formation of Cu 2O(s) from its elements.
Find ΔS°rxn for the formation of HI(g) from its elements.
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.C2H4(g) + H2(g) → C2H6(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.C(s) + H2O(g) → CO(g) + H2(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.CO(g) + H2O(g) → H2(g) + CO2(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.2 H2S(g) + 3 O2(g) → 2 H2O(l) + 2 SO2(g)
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.Cr2O3(s) + 3 CO(g) → 2 Cr(s) + 3 CO2(g)
Find ΔS°rxn for the formation of CH3OH(l) from its elements.
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.N2O4(g) + 4 H2(g) → N2(g) + 4 H2O(g)
Find ΔS˚ for the formation of CH3Cl(g) { m CH}_3{ m Cl}(g) from its elements in their standard states.
Find ΔS˚ for the reaction between nitrogen gas and fluorine gas to form nitrogen trifluoride gas.large{frac{1}{2} m N_2(g);+;frac{3}{2}F_2(g); ightarrow;NF_3(g)}
Consider the following reaction:H2O(g) + Cl 2O(g) → 2HOCl(g)     K 298 = 0.090For Cl2O(g),       ΔG°f = 97.9 kJ/mol       ΔH°f = 80.3 kJ/mol           S° = 266.1 J/K • mold. Estimate ΔH°f and S° for HOCl(g).
For the gaseous reaction of carbon monoxide and chlorine to form phosgene (COCl  2):(a) Calculate ΔS° at 298 K (ΔH° = −220. kJ/mol and ΔG° = −206 kJ/mol).
“Thermite” reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite reaction is Fe2 O3(s) + 2Al(s) ⟶ Al2 O3(s) + 2Fe(s). Is the reaction spontaneous at room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.
By calculating ΔSuniv at each temperature, determine if the melting of 1 mole of NaCl(s) is spontaneous at 500 °C and at 700 °C.What assumptions are made about the thermodynamic information (entropy and enthalpy values) used to solve this problem?
Calculate ΔSsurr for the following reactions at 25°C and 1 atm.a. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)     ΔH° = -2221 kJ
Calculate ΔSsurr for the following reactions at 25°C and 1 atm.b. 2NO2(g) → 2NO(g) + O2(g)              ΔH° = 112 kJ
Determine the normal boiling point (in kelvin) of dichloroethane, CH 2Cl2. Find the actual boiling point using the Internet or some other source, and calculate the percent error in the temperature. Explain the differences, if any, between the two values.