Multiple Choice Questions for Thermodynamics

Multiple Choice Questions for Thermodynamics 

Questions 1-4    

(A) Free energy change (ΔG)  (B) Entropy change (ΔS)  (C) Heat of vaporization  (D) Heat of fusion  (E) Heat capacity    

1. If this has a negative value for a process, then the process occurs spontaneously. 

2. This is a measure of how the disorder of a system is changing. 

3. This is the energy given off when a substance condenses. 

4. This is the energy taken in by a substance when it melts. 

5.  2 Al(s) + 3 Cl​

(g) → 2 AlCl​

(s) 

The reaction above is not spontaneous under standard conditions but becomes spontaneous as the  temperature decreases towards absolute zero. Which of the following is true at standard conditions? 

(A) ΔS and ΔH are both negative. 

(B) ΔS and ΔH are both positive. 

(C) ΔS is negative and ΔH is positive. 

(D) ΔS is positive and ΔH is negative. 

(E) ΔS and ΔH are both equal to zero. 

6. Which of the following is true of the reaction shown in the diagram to the right? 

(A) The reaction is endothermic because the reactants are at a higher  energy level than the products. 

(B) The reaction is endothermic because the reactants are at a lower  energy level than the products. 

(C) The reaction is exothermic because the reactants are at a higher  energy level than the products. 

(D) The reaction is exothermic because the reactants are at a lower energy level than the products. 

(E) The reaction is endothermic because the reactants are at the same energy level as the products. 

7. 2 H​

(g) + O​

(g) → 2 H​

O (g)    

Based on the information given in the table below, what is ΔH​

for the above reaction? 

  Bond  Average bond energy (kJ/mol) 

H-H 500  O=O 500  O-H 500  (A) -2,000 kJ 

(B) -1,500 kJ  (C) -500 kJ  (D) +1,000 kJ  (E) +2,000 kJ    

8. Which of the following is true of a reac​tion that is spontaneous at 298 K but becomes  nonspontaneous at a higher temperature? 

(A) ΔS​

and ΔH​

are both negative. 

(B) ΔS​

and ΔH​

are both positive. 

(C) ΔS​

is negative and ΔH​

is positive. 

(D) ΔS​

is positive and ΔH​

is negative. 

(E) ΔS​

and ΔH​

are both equal to zero    

9. Which of the following will be true when a pure substance in liquid phase freezes spontaneously? 

(A) ΔG, ΔH, and ΔS are all positive. 

(B) ΔG, ΔH, and ΔS are all negative. 

(C) ΔG and ΔH are negative, but ΔS is positive. 

(D) ΔG and ΔS are negative, but ΔH is positive. 

(E) ΔS and ΔH are negative, but Δ G is positive. 

10. 

Which point on the graph shown above corresponds to activated complex, or transition state? 

   (A) 1  (B) 2  (C) 3  (D) 4  (E) 5   

11.  C(s) + O​

(g) → CO​

(g)  ΔH​

= -390 kJ/mol  H​

(g)+ ½ O​

(g) → H​

O (l)  ΔH​

= -290 kJ/mol  2 C(s) + H​

(g) → C​

H​

(g)  ΔH​

= +230 kJ/mol   

Based on the information given above, what is ΔH​

for the following reaction? 

C​

H​

(g) + 5/2 O​

(g) → 2 CO​

(g) + H​

O(l)    

(A) -1300 kJ  (B) -1070 kJ  (C) -840 kJ  (D) -780 kJ  (E) -680 kJ   

12. If an endothermic reaction is spontaneous at 298 K, which of the following must be true for the  reaction?

I. Δ G is greater than zero. 

II. ΔH is greater than zero. 

III. Δ S is greater than zero.

(A) I only 

(B) II only 

(C) I and II only 

(D) II and III only 

(E) I, II, and III 

13. The addition of a catalyst will have which of the following effects on a chemical reaction? 

I. The enthalpy change will decrease. 

II. The entropy change will decrease. 

III. The activation energy will decrease. 

(A) I only  (B) II only  (C) III only  (D) I and II only  (E) II and III only   

14.  C(s) + 2 H​

(g) → CH​

(g)  ΔH​

= x  C(s) + O​

(g) → CO​

(g)  ΔH​

= y  H​

(g) + ½ O​

(g) → H​

O(l)  ΔH​

= z 

Based on the information given above, what is ΔH​

for the following reaction? 

CH​

(g) + 2O​

(g) → CO​

(g) + 2 H​

O(l)  (A) x + y + z 

(B) x + y - z  (C) z + y - 2x  (D) 2z + y - x  (E) 2z + y-2x     

15. For which of the following processes will ΔS be positive? 

  I. NaCl(s) → Na​

(aq) + Cl​

(aq)    II. 2 H​

(g) + O​

(g) → 2 H​

O(g) 

III. CaCO​

(s) → CaO(s) + CO​

(g)    

(A) I only  (B) II only  (C) I and II only  (D) I and III only  (E) I, II, and III    

16. In which of the following reactions is entropy increasing? 

(A) 2SO​

(g) +O​

(g) →2 SO​

(g)  (B) CO (g) + H​

O (g)→H​

(g) + CO​

(g)  (C) H​

(g) + Cl​

(g) → 2 HCl(g)  (D) 2 NO​

(g) →2 NO(g) + O​

(g) 

(E) 2 H​

S(g) + 3 O​

(g) → 2 H​

O(g) + 2 SO​

(g)   

17. When pure sodium is placed in an atmo​sphere of chlorine gas, the following spontaneous  reaction occurs. 

2 Na(s) + Cl​

(g) →2 NaCl(s)   Which of the following statements is true about the reaction? 

I. ΔS > 0  II. ΔH < 0  III. ΔG > 0    

(A) I only  (B) II only  (C) I and II only  (D) II and III only  (E) I, II, and III    

18. 

H​

(g) + F​

(g)→2 HF(g)    

Gaseous hydrogen and fluorine combine in the reaction above to form hydrogen fluoride with an  enthalpy change of -540 kJ. What is the value of the heat of forma​tion of HF(g)? 

(A) -1080 kJ/mol  (B) -540 kJ/mol  (C) -270 kJ/mol  (D) 270 kJ/mol  (E) 540 kJ/mol    

19.  H​

O(s) → H​

O(​l​) 

Which of the following is true of the reaction shown above at room tempera​ture? 

I. ΔG is greater than zero. 

II. ΔH is greater than zero. 

III. ΔS is greater than zero. 

(A) II only  (B) III only  (C) I and II only  (D) I and III only  (E) II and III only 

​ 

20.  2 S(s) + 3 O​

(g)→2 SO​

g)  ΔH = +800kJ/mol  2 SO​

(g)→2 SO​

(g) + O​

(g)  ΔH = -200 kJ/mol 

Based on the information given above, what is ΔH for the following reaction? 

S(s) + O​

(g) →SO​

(g)    

(A) 300 kJ  (B) 500 kJ  (C) 600 kJ  (D) 1000 kJ  (E) 1200 kJ    

Questions 21-25: The set of lettered choices is a list of symbols used in thermodynamics and 

thermochemistry. Select the one lettered choice that best fits each statement. A choice may be used  once, more than once or not at all. 

(A)  K​

(B) ΔG 

(C) ΔH 

(D)  ΔS  (E) E​

21. Its value is negative for any exothermic reaction. 

22. Its value is negative for any spontaneous reaction. 

23. Its value changes when a catalyst is added to the system. 

24. Its value represents the change in randomness as the reaction proceeds. 

25. Its value is determined by using concentrations at equilibrium in the mass action expression. 

Questions 26-28: 

N​

(g) + 3H​

(g) → 2NH​

(g)  ΔH​

= -92 kJ    

The Haber process is a commercial method for the manufacture of ammonia. It is based upon the  equilibrium shown in the equation above. The absolute standard entropies, So, of the components of  this system are given below. 

S​

N​

= 192 J·K​

·mol​

S​

H​

= 131 J·K​

·mol​

S​

NH​

= 193 J·K​

·mol​

26. he value of ΔS​

in J·K​

for the reaction above is closest to    

(A) +200  (B)  +100  (C) 0  (D) -100  (E)  -200    

27. Which interval includes ΔG for this reaction at 200 K, assuming ΔS and ΔH are constant over  a wide range of temperatures? 

(A) less than -100 kJ 

(B) between -100 and -40 kJ  (C) between -40 and +40 kJ  (D)  between -40 and + 100 kJ  (E)  greater than + 100 kJ    

28. Which describes the change in ΔG and the change in spontaneity of the reaction as temperature  increases? 

(A) ΔG decreases to values less than zero and the reaction achieves equilibrium. 

(B) ΔG decreases to values less than zero and the reaction becomes spontaneous. 

(C) ΔG decreases to values less than zero and the reaction becomes non​spontaneous. 

(D) ΔG increases to values greater than zero and the reaction becomes spontaneous. 

(E) ΔG increases to values greater than zero and the reaction becomes non​spontaneous. 

29. The molar heat of fusion, ΔH​

, for water is 6.01 kJ · mol​

. Which expression gives the molar  entropy of fusion, ΔS​

, in kJ·K​

·mol​

for ice at its normal melting point? 

(A) 6.01 

  273 

(B)  6.01 

  298 

(C) 6.01 × 4.18  (D) 6.01 × 273  (E)  6.01 ×298   

30. The molar heat of fusion, ΔH​

, for water is 6.01 kJ·mol​

The specific heat capacity for water, C​

,  is 75 J·mol​

·​

C​

Which expression gives the quantity of energy needed to change 1.0 mol ice at 0​

C  to liquid water at 25​

C? 

(A)  6010    75 × 25  (B)  6.01 + 75 

(C)  6010 + (75 × 25)  (D)  6010​ + (75 × 25) 

  298 

(E)  6010​ + (75 × 25) 

  298 

31. The heat of neutralization for a strong acid in dilute water solution is about 60 kJ. mol​

H​

. What  quantity of heat in kJ is produced when 100 mL of 3.0 M HCI is mixed with 100 mL of 1.0 M KOH? 

(A) 0.10  (B) 0.30  (C) 0.40  (D) 6.0  (E) 18. 

32. All of the following reactions illustrate an increase in entropy EXCEPT    

(A) N​

O​

(g) →2NO​

(g)  (B) C​

H​

(​l​) → C​

H​

(g) 

(C) 2KClO​

(s) → 3O​

(g) + 2KCl (s)  (D) 3Fe(s) + 2O​

(g) → Fe​

O​

(s) 

(E)C​

H​

OH(​l​) + 3O​

(g) → 2CO​

(g) + 3H​

O(g)   

33. For which reaction is ΔH most nearly equal to ΔE? 

(A)  H​

(g) + ½ O​

(g) → H​

O(g)  (B)  H​

(g) + Cl​

(g) → 2HCl(g)  (C) C​

H​

OH(​l​) → C​

H​

OH(g)  (D) N​

O​

(g) → 2NO​

(g)  (E)  BaO​

(s) → BaO​

(s) + O​

(g)    

34. Which equation represents the standard formation reaction for BaSO​

(s) at 298 K? 

(A) BaS(s) + 2O​

(g) → BaSO​

(s)  (B) Ba​

(aq) + SO​

​

(aq) → BaSO​

(s)  (C) Ba(s) + S(s) + 2O​

(g) → BaSO​

(s) 

(D) Ba​

(aq) + S​

(aq) + 4O​

(aq) → BaSO​

(s)  (E) Ba(OH)​

(aq) + H​

SO​

(aq) → BaSO​

(s) + 2H​

O(​l​)    

35. Which describes the thermodynamic parameters for the system H​

O(​s​) → H​

O(​l​) at 298 K? 

  ΔG  ΔH  ΔS 

(A)   0    >0  >0 

(B)    0    >0  <0 

(C)    <0    >0  <0  (D)    < 0    <0  >0  (E)    <0    >0  >0   

36. CH​

(g) + 2O​

(g) → CO​

(g) + 2H​

O(​l​)  ΔH​

= -889 kJ    

ΔH​

for H​

O(​l​) = -286 kJ/mol  ΔH​

for CO​

(g) = -393 kJ/mol    

Which expression gives the standard heat of formation, ΔH​

, for methane, CH​

in kJ/mol based on  the data above? 

(A) -889 + 2(286) + 393 + 2(32)  (B) 889 - 2(286) - 393 - 2(32)  (C) -889 + 2(286) + 393  (D) 889 + 2(286) + 393  (E) 889 - 2(286) - 393    

37. A cube of ice is added to some hot water in an insulated container which is then sealed. There is  no heat exchange with the surroundings. Which describes the system once it has shifted to a new  equilibrium? 

I. The average kinetic energy of the liquid phase has decreased. 

II. The total energy of the system has decreased. 

III. The entropy of the system has increased. 

(A) I only  (B) III only  (C) I and II only  (D) I and III only  (E) I, II, and III    

38. One version of the First Law of Thermodynamics is expressed as  ΔE = q + w 

Which gives the sign convention for this relationship that is usually used in chemistry? 

   heat, q  heat, q  work, w  work, w 

   added  added  done  done 

   to the  to the  on the  on the 

   system  surroundings  system  surroundings 

(A)  -  +  -  - 

(B)  +  +  +  + 

(C)  +  +  +  - 

(D)  +  -  +  - 

(E)  +  -  -  - 

39. The cooling curve above show how the temperature of a sample varies with time as the sample  goes through phase changes. The sample starts as a gas, and heat is removed. at a constant rate. At  which time does the sample contain the most liquid  

  A) t​

B) t​

C) t​

D) t​

E) t​

40. Which applies to any reaction that proceeds spontaneously to form product at initial standard  state conditions? 

I. ΔG <0  II. K​

> 1  III. ΔH <0    

(A) I only  (B) II only  (C) I and II only  (D) II and III only  (E) I, II, and III    

41.  3C(s) + 4H​

(g) → C​

H​

(g)  ΔH​

= -104 kJ  C(s) + O​

g) → CO​

(g)  ΔH​

= -394 kJ  H​

g) + ½ O​

(g) → H​

O(​l​)  ΔH​

= -286 kJ    

Using the values above, which expression gives the heat of combustion, ΔH​

for propane, C​

H​

,  in kJ/mol? 

C​

H​

g) + 5O​

g) → 3CO​

(g) + 4H​

O(​l​)  ΔH​

=? 

(A) (- 104) - (394 + (- 286))   

(B)  (- 394 + (-286)) - (- 104)   

(C) (- 104) - ( - 3 × 394 + (-4 × 286))   

(D) (-104) + ( -3×394+(-4×286))   

(E)  (-3×394 + (-4 × 286)) - (-104)   

42.  2C(s) + 3H​

(g) → C​

H​

(g)    

The reaction above is not spontaneous at any temperature. Which applies to the system at 298 K? 

ΔG  ΔH  ΔS 

(A)  +    +    + 

(B)  +    +    - 

(C)  -    +    - 

(D)  -  -    - 

(E)  -  -  + 

43. Which applies to any reaction that has negative values for both ΔH and ΔS? 

  I. The reaction is spontaneous at all temperatures. 

  II. The reaction is exothermic. 

III. ΔG increases (becomes more positive) as temperature increases. 

(A) I only  (B) III only  (C) I and III only  (D) II and III only  (E) I, II, and III    

44. For a given reaction, the values for standard free energy change, ΔG​

, and the equi​librium  constant, K​

, are both measures of the extent to which a reaction proceeds. Which range includes  the value for ΔG​

(at 298 K) in kilojoules, when the corre​sponding value for K​

is 1 × 10​

? 

(A) less than 20  (B)  20 to 40  (C) 40 to 80  (D) 80 to 160 

(E)  greater than 160    

45. One version of the Second Law of Thermodynamics for any spontaneous process includes the  statement 

ΔSuniverse = (ΔSsystem + ΔSsurroundings) > 0    

Which is the best interpretation of this statement? 

(A) For any spontaneous process, the entropy of the universe increases. 

(B) For any spontaneous process, the free energy change is negative. 

(C) For any spontaneous process, the entropy change for the system is positive. 

(D)For any spontaneous process, the entropy change for the system is less than the entropy change  for the surroundings. 

(E)For any spontaneous process, the entropy change for the system is greater than the entropy  change for the surroundings. 

46. Lead (II) oxide is reduced with carbon to produce metallic lead, with the thermochemical  equation: 

PbO(s) + C(s) → Pb(s) + CO(g)  ΔH= + 106.8 kJ/mol    

This is _____________reaction, which ______________heat. 

A. a formation; absorbs  B. an exothermic; absorbs  C. an exothermic; releases  D. an endothermic; absorbs  E. an endothermic; releases    

47. Lead has been known and used for centuries. The first step to obtain the metal is to roast the  mineral containing lead (II) sulfide in air to form lead (II) oxide: 

PbS(s) + 3/2 O​

(g) → PbO (s) + SO​

(g)  ΔH= -414 kJ/mol    

What is the enthalpy change for the burning of 1.00 kilogram of solid lead (II) sulfide? 

A. -1730 kJ  B. -414 kJ  C. -1.73 kJ  D. +414 kJ  E. +1730 kJ    

48. Solid sulfur can be burned to produce sulfur dioxide gas, with the following thermochemical  equation: 

S(s) + O​

(g) → SO​

(g)  ΔH= -296 kJ/mol    

The burning of 1.00 kilogram of solid sulfur is used to heat 250.0 L of water. Assuming all of the  energy is used to heat the water, and none is lost to the surroundings, what will the final 

temperature of the water be in kelvins, if the initial temperature is 25.0°C? 

A. 33.8 K  B. 239.4 K  C. -239.4 K  D. 25.0 K  E. 307.0 K    

49. As a solid carbon sample burns completely it produces carbon dioxide gas, with the  thermochemical equation:  

C(s) + O​

(g) → CO​

(g)  ΔH= -293.5 kJ/mol    

What is relationship between the enthalpy change and the heat of reaction for the burning of solid  carbon at atmospheric pressure? 

A. The enthalpy change is less than the heat of reaction at atmospheric pressure. 

B. The enthalpy change is equal to the heat of reaction at atmospheric pressure. 

C. The enthalpy change is greater than the heat of reaction at atmospheric pressure. 

D. The enthalpy change is equal to the internal energy change, but not to the heat of reaction. 

E. Any thermodynamic relationship must be determined at constant volume, not at constant 

pressure. 

50. Solid sulfur is burned to produce sulfur dioxide gas: 

S(s) + O​

(g) → SO​

(g)  ΔH= -296 kJ/mol    

The heat released by burning 1.00 kilogram of solid sulfur is captured by 250.0 L of water. Assuming  all of the energy is used to heat the water, and none is lost to the surroundings, what will the final  temperature of the water be in degrees Celsius if the initial temperature is 25.0°C? The specific heat  of water is 4.18 J/g°K. 

A. 16.2°C  B. 25.0°C  C. 33.8°C  D. 154.0°C  E. 179.0°C    

51. Enthalpy changes are determined experimentally for these reactions: 

​Pb(s) + 2 Cl​

(g) → PbCl​

(​l​)  ΔH = -329.3 kJ  PbCl​

(s) + Cl​

(g) → PbCl​

(​l​)  ΔH= +30.1 kJ    

What is the enthalpy change for the reaction of lead with chlorine to give lead (II) chloride, PbCl​

?    

A. -359.4  B. -329.3  C. -299.2  D. +30.1  E. +359.4   

​52. The specific heat capacity of ethanol is 2.4 J/g*K and its density is 0.789 g/mL. A 250.0 mL 

sample of ethanol is heated from 25.0°C to 47.0°C at constant pressure. How much energy was added  to the sample of ethanol? 

A. 1.3 × 10​

J  B. 1.0 ×10​

J  C. 2.2 × 10​

J  D. 2.8 × 10​

J  E. 4.3 × 10​

J    

53. Hydrogen gas is burned to form steam: 

H​

(g) + ½ O​

(g) → H​

O(g)  ΔH= -241.8 kJ 

The heat capacity, C​

, of aluminum is 0.90 J/g°K. How many grams of hydrogen gas is burned in the  production of enough energy to raise the temperature of a 15.0 kg sample of aluminum by 6.5°C? 

A. 0.36 g  B. 0.73 g  C. 0.88 g  D. 0.90 g  E. 2.8 g    

54. The combustion of gaseous diborane, B​

H​

, proceeds according to the equation: 

B​

H​

(g) + 3 O​

g) → B​

O​

(s) + 3 H​

O(g)  ΔH= -1941 kJ    

What is the enthalpy change for the reaction of boron oxide with water vapor to produce diborane  gas and oxygen gas? 

A. -3882 kJ  B. -1941 kJ  C. +970.5 kJ  D. +1941 kJ  E. + 3882 kJ    

55. The thermochemical equation for the combustion of hydrogen gas to form water vapor is: 

H​

(g) + ½ O​

(g) → H​

O(g)  ΔH = -241.8 kJ    

How many grams of hydrogen gas are consumed in the release 3580 kJ of energy? 

A. 7.33 g  B. 7.40 g  C. 14.8 g  D. 15.0 g  E. 29.8 g    

56. A reaction with a negative ΔG is: 

A. spontaneous  B. nonspontaneous  C. exothermic  D. endothermic  E. non-thermic   

57. Which processes are spontaneous? 

  I. A scoop of ice cream melting on a hot summer day. 

  II. A snowball rolling up a hill. 

III. NaCl (s) dissolving into Na​

(aq) and Cl​

(aq) ions when added to water. 

IV. A book falling off of a shelf. 

V. Water freezing at 1 atm and -5°C. 

A. I and II only  B. I and IV only  C. I, III, and V  D. I, III, IV, and V  E. I, III, and IV    

58. For the reaction 2C(s) + 3H​

(g) →C​

H​

(g) the entropy change at 25°C (J / mol·K) is: 

   S° (J/mol·K) 

C (s)  5.74 

C​

H​

(g)  229.5  H​

(g)  130.6    

A. -173.8  B. -162.3  C. -150.9  D. 93.2  E. 229.5    

59. What is the standard enthalpy change for the reaction of methane with oxygen to form carbon  dioxide, carbon monoxide, and steam? 

4 CH​

(g) + 7 O​

(g) →2 CO​

(g) + 2 CO (g) + 8 H​

O (g)    

   ΔH (kJ/mol) 

CH​

(g)  -74.9  O​

(g)  0  CO​

(g)  -393.5 

CO (g)  -110.5 

H​

(g)  -241.8    

A. -2642.8 kJ  B. -3242.0 kJ  C. 2200.8 kJ  D. 9.82 kJ 

E. 1.02 × 10-1 kJ    

60. For a reaction, ΔS is positive and ΔH is positive. In what temperature range is the reaction  spontaneous? 

A. The reaction is always spontaneous. 

B. The reaction is never spontaneous. 

C. The reaction is spontaneous at T > ΔH/ΔS. 

D. The reaction is spontaneous at T < ΔH/ΔS. 

E. The reaction is spontaneous at T = ΔH/ΔS. 

61. For the reaction HBr (g) → ½ H​

(g) + ½ Br​

(g) , calculate the free-energy change, ΔG​

, in  kilojoules. The free energy of formation of HBr is -53.43 kJ/mol and Br​

(g) is 3.144 kJ/mol. 

A. -51.86  B. -50.29  C. +53.43  D. +55.00  E. +56.57    

62. Sulfur dioxide reacts with oxygen to produce sulfur trioxide. At what temperature is the  reaction spontaneous? 

2SO​

(g) + O​

(g) → 2SO​

(g)  ΔH​

= -198 kJ/mol  ΔS​

= -0.187 kJ/mol·K  A. The reaction is always spontaneous. 

B. The reaction is never spontaneous. 

C. The reaction is spontaneous at temperatures above 1060 K. 

D. The reaction is spontaneous at temperatures below 1060 K. 

E. The reaction is spontaneous at temperatures below room temperature. 

63. Which describes the equilibrium constant for a spontaneous reaction? 

   A. K=O  B. K<O  C. K=1  D. K<1  E. K> 1    

64. Which of is true at equilibrium? 

A. Q=O  B. K=O  C. Q=K  D. ΔG > 0  E. ΔG​

= 1    

65. For which reaction is ΔS​

< 0? 

A. C​

H​

(s) →C​

H​

(​l​)  B. 2IBr (g) → I​

(s) + Br​

(​l​)  C. 2NO​

(g) → N​

(g) + 2O​

(g)  D. NH​

CI (s) → NH​

(g) + HCl (g) 

E. (NH​

)​

CO​

(s) → 2 NH​

(g) + H​

O (g) + CO​

(g)    

66. Calculate the equilibrium constant at 25°C for the reaction: 

3C(s) + 4 H​

(g) → C​

H​

(g)    

The free energy of formation of the C​

H​

s ΔG​

= -23.49 kJ/mol·K    

A. 3.0 × 10​

B. 1.3 ×10​

C. 1.0  D. 7.6 × 10​

E. 3.3 × 10​

67. When 0.400 g of CH​

is burned in excess oxygen in a bomb calorimeter that has a heat capacity  of 3245 J​

C​

, a temperature increase of 6.795°C is observed. What is the value of q​

? 

(A) 220 kJ mol​

(B) -882 kJ  (C) 477 kJ  (D) -22.05 kJ  (E) .8.820 kJ g​

68. Using the data in ​question 67​, determine ΔH​

for the combustion of methane. 

(A) -22.05 kJ mol​

(B) -882 kJ 

(C) +22.05 kJ  (D) -8.820 kJ g​

(E) This value cannot be determined because w is not known. 

69. Which of the following describes a system that CANNOT be sponta​neous? 

(A) ΔH​

is positive, and ΔS​

is negative. 

(B) ΔH​

is positive, and ΔS​

is positive. 

(C) ΔH​

is negative, and ΔS​

is negative. 

(D) ΔH​

is negative, and ΔS​

is positive. 

(E) ΔH​

is 0.00, and ΔS​

is positive. 

70. Which of the following explains the fact that, when KCl is dissolved, water condenses on the  outside of the beaker? 

(A) ΔH​

is positive, and ΔS​

is negative. 

(B) ΔH​

is positive, and ΔS​

is positive. 

(C) ΔH​

is negative, and ΔS​

is negative. 

(D) ΔH​

is negative, and ΔS​

is positive. 

(E) ΔH​

is 0.00, and ΔS​

s negative. 

71. The reaction with the greatest expected entropy decrease is    

(A) CH​

(g) + 2O​

(g) →CO​

(g) + 2H​

O(g)  (B) CH​

(​l​) + 2O​

(g) →CO​

(g) + 2H​

O(g)  (C) CH​

(g) + 2O​

(g) →CO​

(g) + 2H​

O(​l​)  (D) CH​

(g) + 2O​

(g) →CO​

(g) + 2H​

O(g)  (E) CH​

(​l)​ + 2O​

(g) →CO​

(g) + 2H​

O(​l​)    

72. Water boils at 100°C with a molar heat of vaporization of +43.9 kJ. What is the entropy change  when H​

O(g) → H​

O(​l​) at 100°C? 

(A) Problem cannot be solved; ΔG​

must also be known. 

(B) Problem cannot be solved; this is not a chemical reaction. 

(C) -439 J K-l  (D) +0.439 J K-l  (E) -118 J K-l    

73. Which of the following is the quantity that would be zero for a pure, perfect crystal at 0K.  

A) Activation Energy  B) Enthalpy of formation  C) Entropy 

D) Gibbs Free Energy  E) Lattice Energy   

74. Which of the following is the LEAST probable for a combustion reaction? 

(A) ΔG​

is a large negative number. 

(B) ΔS​

is a large negative number. 

(C) ΔH​

is a large negative number. 

(D) K​

is a large positive number. 

(E) Q, the reaction quotient, is a small number.  

75. Calculate the mass of gold that requires 468 J to heat the sample from 21.6​

C to 33.2​

C. The  specific heat of gold is 0.130 J/g​

C  

A) 6.72 g  B) 483 g  C) 310 g  D) 63.4 g   

76. The heat of formation of CH​

OH (​l​) = -238.6 kJ mol​

, of CO​

(g) = -393.5 kJ mol​

and of H​

O (g) =  -241.8 kJ mol-l; What is ΔH​

or the heat of combustion of methanol? 

(A) -396.7 kJ  (B) -1277 kJ  (C) -638.5 kJ  (D) + 396.7 kJ 

(E) This value cannot be calculated without the heat of formation for O​

(g). 

77. The rate of reaction will be large if    

(A) ΔG​

is a large negative number. 

(B) ΔS​

is a large negative number. 

(C) ΔH​

is a large negative number. 

(D) K​

is a large positive number. 

(E) Q, the reaction quotient, is a small number. 

78. Given the following thermochemical data: 

N​

O​

(g) → 2NO​

(g)  ΔH​

= +57.93 kJ  2NO(g) + O​

g) →2NO​

(g)  ΔH​

= -113.14 kJ  determine the heat of the reaction for 2NO(g) +O​

(g) →N​

O​

(g). 

(A) 171.07 kJ  (B) -55.21 kJ  (C) -171.07 kJ  (D) + 55.21 kJ  (E) -85.54 kJ   

79. Which of the following can change the value of ΔG​

for a chemical reaction? 

(A) changes in the total pressure 

(B) changes in the pressures of the reactants  (C) changes in the concentrations of the, reactants  (D) changes in the temperature in °C 

(E) the presence of a catalyst    

80. At what temperature is K​

= 1.00 if ΔS​

= 22.6 J K​

and ΔH​

= 15.3 kJ for a chemical reaction? 

(A) 404°C  (B) 677°C  (C) 0.67°C  (D) 1477°C  (E) 1204°C    

81. The standard heat of formation of SO​

(g) is -396 kJ mol​

The stand​ard entropies of S(s), O​

(g), and  SO​

(g) are 31.8, 205.0, and 256 J mol​

K​

respectively. Calculate the free energy for the 

decomposition of SO​

in the reaction 

2SO​

(g)→2S(s)+3O​

(g) at 25°C. 

(A) 396 kJ  (B) 446 kJ  (C) 346 kJ  (D) -346 kJ  (E) 742 kJ    

82. The reaction 2C​

H​

(​l​) + 15O​

(g) →12CO​

(g) + 6H​

O (​l​) is expected to have. 

(A) a positive ΔH and a negative ΔS  (B) a negative ΔH and a negative ΔS  (C) a positive ΔH and a positive ΔS  (D) a negative ΔH and a positive ΔS  (E) These predictions cannot be made. 

83. The evaporation of any liquid is expected to have    

(A) a positive ΔH and a negative ΔS 

(B) a negative ΔH and a negative ΔS 

(C) a positive ΔH and a positive ΔS 

(D) a negative ΔH and a positive ΔS 

(E) These predictions cannot be made. 

84. Which of the following is most likely to be true? 

(A) No products are formed in a nonspontaneous reaction. 

(B) A positive ΔG​

indicates a spontaneous reaction. 

(C) A positive ΔS​

always means that the reaction is spontaneous. 

(D) A spontaneous reaction always goes to completion. 

(E) Combustion of organic compounds has a negative ΔH​

.   

85. Which of the following is NOT an endothermic process? 

A) condensation of water  B) boiling soup 

C) water evaporating  D) Ice Melting  

E) Carbon dioxide sublimating    

Questions 86-88 refer to the following combination of enthalpy changes, (ΔH) and entropy changes  (ΔS) for chemical reactions  

A) ΔH > 0, ΔS > 0  B) ΔH > 0, ΔS < 0  C) ΔH < 0, ΔS > 0  D) ΔH < 0, ΔS < 0  E) ΔH = 0, ΔS < 0   

86. Must be true for a reaction that is spontaneous at all temperatures   

87. True for the evaporation of water at 25​

C   

88. True for the combination of liquid pentane, C​

H​

(l) to form H​

O (g) and CO​

(g) at 1 atm.  

89. Based on the reaction shown, which statement is true   

N​

+ O​

→ 2NO ΔH = 43.2 kcal   

A) 43.2 kcal are consumed when 1.00 mol of O​

reacts  B) 43.2 kcal are produced when 1.00 mol of NO is produced  C) 43.2 kcal are consumed when 1.00 g of N​

reacts 

D) 43.2 kcal are consumed when 1.00 g of O​

reacts