Chemistry And Chemical Reactivity International Edition 8th Edition By John C. Kotz - Test Bank

Chemistry And Chemical Reactivity International Edition 8th Edition By John C. Kotz – Test Bank

 

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Sample Questions Are Posted Below

 

Chapter 5—Principles of Chemical Reactivity: Energy and Chemical Reactions

 

MULTIPLE CHOICE

 

1. Which of the following statements is/are CORRECT?

	1.	A system is defined as an object or collection of objects being studied.
	2.	Surroundings are defined as the entire universe, including the system.
	3.	In an endothermic reaction, heat is transferred from the system to the surroundings.

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 3
e.	1, 2, and 3

 

 

ANS:  A

 

2. A hot piece of iron is dropped into a beaker containing colder water. Which of the following statements is/are CORRECT?

	1.	Energy is transferred as heat from the iron to the water.
	2.	Thermal equilibrium is attained when the iron and the water reach the same temperature.
	3.	Thermal energy from the iron is converted to electrostatic energy in the water.

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 2
e.	1, 2, and 3

 

 

ANS:  D

 

3. Which one of the following statements is INCORRECT?

a.	Energy is neither created nor destroyed in chemical reactions.
b.	Kinetic energy is the energy that results from an object’s position.
c.	Exothermic processes transfer heat from the system into the surroundings.
d.	Increasing the thermal energy of a gas increases the motion of its atoms.
e.	Energy is the capacity to do work.

 

 

ANS:  B

 

4. Many homes are heated using natural gas. The combustion of natural gas converts

a.	chemical potential energy to thermal energy.
b.	thermal energy to mechanical energy.
c.	mechanical energy to chemical potential.
d.	electrostatic energy to mechanical energy.
e.	gravitational energy to acoustic energy.

 

 

ANS:  A

 

 

5. Which of the following processes is/are endothermic?

	1.	the combustion of hydrogen
	2.	the condensation of water
	3.	the evaporation of isopropyl alcohol

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 3
e.	1, 2, and 3

 

 

ANS:  C

 

6. Which of the following processes is/are exothermic?

	1.	the reaction of butane with oxygen
	2.	the melting of gold
	3.	cooling copper from 225 °C to 65 °C

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 3
e.	1, 2, and 3

 

 

ANS:  D

 

7. Specific heat capacity is

a.	the quantity of heat needed to change the temperature of 1.00 g of a substance by 1 K.
b.	the quantity of heat needed to change the temperature of 1.00 g of a substance by 4.184 K.
c.	the capacity of a substance to gain or lose a 1.00 J of energy in the form of heat.
d.	the temperature change undergone when 1.00 g of a substance absorbs 4.184 J.
e.	the maximum amount of energy in the form of heat that 1.00 g of a substance may absorb without decomposing.

 

 

ANS:  A

 

8. Heat capacity is defined as

a.	the amount of heat required to raise the temperature of 1 gram of substance by 1 K.
b.	the amount of heat required to raise the temperature of a substance by 1 K.
c.	the amount of heat required to vaporize a solid or liquid.
d.	the maximum amount of heat that a substance may absorb without decomposing.
e.	4.18 cal/g×K.

 

 

ANS:  B

 

 

9. Which of the following statements is/are CORRECT?

	1.	Specific heat capacity is a positive value for liquids and solids and a negative value for gases.
	2.	The larger the heat capacity of an object, the more thermal energy it can store.
	3.	When heat is transferred from the surroundings to the system, q is negative.

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 2
e.	1, 2, and 3

 

 

ANS:  B

 

10. If 495 J is required to change the temperature of 12.7 g of sodium chloride from 275.0 K to 335.0 K, what is the specific heat capacity of sodium chloride?

a.	0.866 J/g×K
b.	2.60 J/g×K
c.	0.650 J/g×K
d.	1.15 J/g×K
e.	2.83 ´ 105 J/g×K

 

 

ANS:  C

 

11. If the same amount of energy in the form of heat is added to 5.00 g samples of each of the metals below, which metal will undergo the largest temperature change?

 

	Metal	Specific Heat Capacity (J/g×K)
	Ag	0.235
	Al	0.897
	Cu	0.385
	Fe	0.449
	Hg	0.140

 

a.	Ag
b.	Al
c.	Cu
d.	Fe
e.	Hg

 

 

ANS:  E

 

12. If 50.0 g of benzene, C₆H₆, at 25.0 °C absorbs 2.71 kJ of energy in the form of heat, what is the final temperature of the benzene? The specific heat capacity of benzene is 1.72 J/g×K.

a.	25.0 °C
b.	31.5 °C
c.	56.5 °C
d.	32.3 °C
e.	57.3 °C

 

 

ANS:  C

 

 

13. How much energy (in kJ) is required to change the temperature of 325 g aluminum from 32 °C to 815 °C? The specific heat capacity of aluminum is 0.897 J/g×K.

a.	238 kJ
b.	284 kJ
c.	46.3 kJ
d.	228 kJ
e.	2.16 kJ

 

 

ANS:  D

 

14. If 35.0 g H₂O at 22.7 °C is combined with 65.0 g H₂O at 87.5 °C, what is the final temperature of the mixture? The specific heat capacity of water is 4.184 J/g×K.

a.	25.1 °C
b.	45.4 °C
c.	50.8 °C
d.	64.8 °C
e.	48.9 °C

 

 

ANS:  D

 

15. If 46.1 g Cu at 11.6 °C is placed in 85.0 g H₂O at 72.4 °C, what is the final temperature of the mixture? The specific heat capacities of copper and water are 0.385 J/g×K and 4.184 J/g×K, respectively.

a.	71.2 °C
b.	63.6 °C
c.	51.0 °C
d.	42.0 °C
e.	69.5 °C

 

 

ANS:  E

 

16. When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H₂O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g×K.

a.	0.055 J/g×K
b.	0.29 J/g×K
c.	0.69 J/g×K
d.	0.18 J/g×K
e.	2.6 J/g×K

 

 

ANS:  B

 

17. Calculate the energy in the form of heat (in kJ) required to convert 325 grams of liquid water at 20.0 °C to steam at 115 °C. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g; specific heat capacities: liquid water = 4.184 J/g×K, steam = 1.92 J/g×K)

a.	129 kJ
b.	121 kJ
c.	851 kJ
d.	914 kJ
e.	735 kJ

 

 

ANS:  C

 

18. Calculate the energy in the form of heat (in kJ) required to change 75.0 g of liquid water at 27.0 °C to ice at –20.0 °C. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g; specific heat capacities: ice = 2.06 J/g×K, liquid water = 4.184 J/g×K)

a.	–13.4 kJ
b.	–17.7 kJ
c.	–36.5 kJ
d.	–10.2 kJ
e.	–30.3 kJ

 

 

ANS:  C

 

19. 44.0 g of ice at –20.0 °C is mixed with 325 g of water at 32.1 °C. Calculate the final temperature of the mixture. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; specific heat capacities: ice = 2.06 J/g×K, liquid water = 4.184 J/g×K)

a.	–0.6 °C
b.	5.5 °C
c.	12.1 °C
d.	17.6 °C
e.	38.9 °C

 

 

ANS:  D

 

20. What is the minimum mass of ice at 0.0 °C that must be added to 1.00 kg of water to cool the water from 28.0 °C to 12.0 °C? (Heat of fusion = 333 J/g; specific heat capacities: ice = 2.06 J/g×K, liquid water = 4.184 J/g×K)

a.	175 g
b.	201 g
c.	244 g
d.	299 g
e.	1140 g

 

 

ANS:  A

 

21. The heat of vaporization of benzene, C₆H₆, is 30.7 kJ/mol at its boiling point of 80.1 °C. How much energy in the form of heat is required to vaporize 102 g benzene at its boiling point?

a.	0.302 kJ
b.	23.6 kJ
c.	24.2 kJ
d.	40.1 kJ
e.	3.14 ´ 103 kJ

 

 

ANS:  D

 

22. One statement of the first law of thermodynamics is that

a.	the amount of work done on a system is dependent of the pathway.
b.	the total work done on a system must equal the heat absorbed by the system.
c.	the total work done on a system is equal in magnitude, but opposite in sign of the heat absorbed by the system.
d.	the total energy change for a system is equal to the sum of the heat transferred to or from the system and the work done by or on the system.
e.	in any chemical process the heat flow must equal the change in enthalpy.

 

 

ANS:  D

 

23. Which of the following statements is/are CORRECT?

	1.	If a reaction occurs at constant pressure, q = DH.
	2.	The change in energy for a system is defined as the sum of the energies transferred as heat and work (i.e., DU = q + w).
	3.	If a reaction occurs at constant volume, q = w

 

a.	1 only
b.	2 only
c.	3 only
d.	1 and 2
e.	1, 2, and 3

 

 

ANS:  D

 

24. Which of the following thermodynamic quantities are state functions: heat (q), work (w), enthalpy change (DH), and/or internal energy change (DU)?

a.	q only
b.	w only
c.	DH only
d.	DU only
e.	DH and DU

 

 

ANS:  E

 

25. The thermochemical equation for the combustion of methanol is shown below.

CH3OH() + 3/2 O2(g) ® CO2(g) + 2 H 2O(g)

DrH° = –638.7 kJ/mol-rxn

What is the enthalpy change for the combustion of 8.59 g CH₃OH?

a.	–171 kJ
b.	–19.9 kJ
c.	–2.38 ´ 103 kJ
d.	–5.49 ´ 103 kJ
e.	–1.76 ´ 106 kJ

 

 

ANS:  A

 

26. The thermochemical equation for the combustion of butane is shown below.

C4H10(g) + 13/2 O2(g) ® 4 CO2(g) + 5 H2O()

DrH° = –2877 kJ/mol-rxn

What is the enthalpy change for the following reaction?

8 CO₂(g) + 10 H₂O() ® 2 C₄H₁₀(g) + 13 O₂(g)

a.	+1439 kJ/mol-rxn
b.	+2877 kJ/mol-rxn
c.	–5754 kJ/mol-rxn
d.	–2877 kJ/mol-rxn
e.	+5754 kJ/mol-rxn

 

 

ANS:  E

 

 

27. Iron oxide reacts with aluminum in an exothermic reaction.

Fe₂O₃(s) + 2 Al(s) ® 2 Fe(s) + Al₂O₃(s)

The reaction of 5.00 g Fe₂O₃ with excess Al(s) evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe₂O₃ reacted.

a.	–5.32 kJ/mol
b.	–1.33 ´ 102 kJ/mol
c.	–2.12 ´ 104 kJ/mol
d.	–2.12 ´ 102 kJ/mol
e.	–8.50 ´ 102 kJ/mol

 

 

ANS:  E

 

28. Hydrazine, N₂H₄, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water.

N₂H₄() + O₂(g) ® N₂(g) + 2 H₂O()

The reaction of 6.50 g N₂H₄ evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.

a.	–19.4 kJ/mol
b.	–25.6 kJ/mol
c.	–126 kJ/mol
d.	–622 kJ/mol
e.	–820. kJ/mol

 

 

ANS:  D

 

29. CaO(s) reacts with water to form Ca(OH)₂(aq). If 6.50 g CaO is combined with 99.70 g H₂O in a coffee cup calorimeter, the temperature of the resulting solution increases from 21.7 °C to 43.1 °C. Calculate the enthalpy change for the reaction per mole of CaO. Assume that the specific heat capacity of the solution is 4.18 J/g×K.

a.	–1.45 kJ/mol
b.	–82.0 kJ/mol
c.	–9.42 kJ/mol
d.	–165 kJ/mol
e.	–532 kJ/mol

 

 

ANS:  B

 

30. Commercial cold packs consist of solid ammonium nitrate and water. NH₄NO₃ absorbs 25.69 kJ of heat per mole dissolved in water. In a coffee-cup calorimeter, 5.60 g NH₄NO₃ is dissolved in 100.0 g of water at 22.0 °C. What is the final temperature of the solution? Assume that the solution has a specific heat capacity of 4.18 J/g×K.

a.	0.0 °C
b.	17.9 °C
c.	11.6 °C
d.	–54.8 °C
e.	26.1 °C

 

 

ANS:  B

 

 

31. When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 25.18 °C to 47.53 °C. What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g×K.

a.	–116 J/g
b.	–934 J/g
c.	–1.03 ´ 103 J/g
d.	–2.19 ´ 103 J/g
e.	–1.03 ´ 104 J/g

 

 

ANS:  C

 

32. A chemical reaction in a bomb calorimeter evolves 3.86 kJ of energy in the form of heat. If the temperature of the bomb calorimeter increases by 4.17 K, what is the heat capacity of the calorimeter?

a.	3.87 ´ 103 J/K
b.	311 J/K
c.	926 J/K
d.	1.8 ´ 103 J/K
e.	1.61 ´ 104 J/K

 

 

ANS:  C

 

33. A 1.994 g sample of ethanol, CH₃CH₂OH, is combusted in a bomb calorimeter. The temperature of the calorimeter increases by 10.91 K. If the heat capacity of the bomb is 615.5 J/K and it contains 1.150 kg of water, what is the enthalpy change per mole of ethanol combusted? The specific heat capacity of water is 4.184 J/g×K and the molar mass of ethanol is 46.07 g/mol.

a.	–5.921 ´ 101 kJ/mol
b.	–2.563 ´ 103 kJ/mol
c.	–1.181 ´ 105 kJ/mol
d.	–1.368 ´ 103 kJ/mol
e.	–122.7 ´ 103 kJ/mol

 

 

ANS:  D

 

34. Acetylene, C₂H₂, is a gas used in welding. The molar enthalpy of combustion for acetylene is –2599 kJ. A mass of 0.338 g C₂H₂(g) is combusted in a bomb calorimeter. If the heat capacity of the calorimeter is 729 J/K and it contains 1.150 kg of water, what is the temperature increase of the bomb calorimeter? The specific heat capacity of water is 4.184 J/g×K and the molar mass of acetylene is 26.04 g/mol.

a.	1.59 K
b.	6.09 K
c.	7.01 K
d.	12.3 K
e.	18.0 K

 

 

ANS:  B

 

 

35. Determine the heat of evaporation of carbon disulfide,

CS₂() ® CS₂(g)

given the enthalpies of reaction below.

	C(s) + 2 S(s) ® CS2()	DrH° = +89.4 kJ/mol-rxn
	C(s) + 2 S(s) ® CS2(g)	DrH° = +116.7 kJ/mol-rxn

 

a.	–206.1 kJ
b.	–27.3 kJ
c.	+27.3 kJ
d.	+206.1 kJ
e.	+1.31 kJ

 

 

ANS:  C

 

36. Determine the standard enthalpy of formation of Fe₂O₃(s) given the thermochemical equations below.

	Fe(s) + 3 H2O() ® Fe(OH)3(s) + 3/2 H2(g)	DrH° = +160.9 kJ/mol-rxn
	H2(g) + 1/2 O2(g) ® H2O()	DrH° = –285.8 kJ/mol-rxn
	Fe2O3(s) + 3 H2O() ® 2 Fe(OH)3(s)	DrH° = +288.6 kJ/mol-rxn

 

a.	–252.6 kJ/mol-rxn
b.	+163.7 kJ/mol-rxn
c.	–824.2 kJ/mol-rxn
d.	+33.2 kJ/mol-rxn
e.	+ 890.6 kJ/mol-rxn

 

 

ANS:  C

 

37. Determine the enthalpy change for the oxidation of ethanol to acetic acid,

CH₃CH₂OH() + O₂(g) ® CH₃COOH() + H₂O()

given the thermochemical equations below.

	2 CH3CH2OH() + O2(g) ® 2 CH3CHO() + 2 H 2O()	DrH° = –400.8 kJ/mol-rxn
	2 CH3CHO() + O2(g) ® 2 CH3COOH()	DrH° = –584.4 kJ/mol-rxn

 

a.	–985.2 kJ/mol-rxn
b.	–492.6 kJ/mol-rxn
c.	–183.6 kJ/mol-rxn
d.	+183.6 kJ/mol-rxn
e.	+492.6 kJ/mol-rxn

 

 

ANS:  B

 

 

38. Determine the enthalpy change for the decomposition of calcium carbonate

CaCO₃(s) ® CaO(s) + CO₂(g)

given the thermochemical equations below.

	Ca(OH)2(s) ® CaO(s) + H2O()	DrH° = 65.2 kJ/mol-rxn
	Ca(OH)2(s) + CO2(g) ® CaCO3(s) + H2O()	DrH° = -113.8 kJ/mol-rxn
	C(s) + O2(g) ® CO2(g)	DrH° = -393.5 kJ/mol-rxn
	2 Ca(s) + O2(g) ® 2 CaO(s)	DrH° = -1270.2 kJ/mol-rxn

 

a.	+48.6 kJ/mol-rxn
b.	+179.0 kJ/mol-rxn
c.	+345.5 kJ/mol-rxn
d.	+441.0 kJ/mol-rxn
e.	+1711.7 kJ/mol-rxn

 

 

ANS:  B

 

39. Determine D_rH° for the following reaction,

2 NH₃(g) + 5/2 O₂(g) ® 2 NO(g) + 3 H₂O(g)

given the thermochemical equations below.

	N2(g) + O2(g) ® 2 NO(g)	DrH° = +180.8 kJ/mol-rxn
	N2(g) + 3 H2(g) ® 2 NH3(g)	DrH° = –91.8 kJ/mol-rxn
	2 H2(g) + O2(g) ® 2 H2O(g)	DrH° = –483.6 kJ/mol-rxn

 

a.	–1178.2 kJ/mol-rxn
b.	–452.8 kJ/mol-rxn
c.	–394.6 kJ/mol-rxn
d.	–211.0 kJ/mol-rxn
e.	+1178.2 kJ/mol-rxn

 

 

ANS:  B

 

40. Determine the standard enthalpy of formation of calcium carbonate from the thermochemical equations given below.

	Ca(OH)2(s) ® CaO(s) + H2O()	DrH° = 65.2 kJ/mol-rxn
	Ca(OH)2(s) + CO2(g) ® CaCO3(s) + H2O()	DrH° = -113.8 kJ/mol-rxn
	C(s) + O2(g) ® CO2(g)	DrH° = -393.5 kJ/mol-rxn
	2 Ca(s) + O2(g) ® 2 CaO(s)	DrH° = -1270.2 kJ/mol-rxn

 

a.	-1712.3 kJ/mol-rxn
b.	-441.8 kJ/mol-rxn
c.	-849.6 kJ/mol-rxn
d.	-980.6 kJ/mol-rxn
e.	-1207.6 kJ/mol-rxn

 

 

ANS:  E

 

 

41. Which of the following chemical equations corresponds to the standard molar enthalpy of formation of Na₂CO₃(s)?

a.	2 Na(s) + C(s) + 3 O(g) ® Na2CO3(s)
b.	Na2O(s) + CO2(g) ® Na2CO3(s)
c.	Na2(s) + C(s) + 3 O(g) ® Na2CO3(s)
d.	Na2O2(s) + CO(g) ® Na2CO3(s)
e.	2 Na(s) + C(s) + 3/2 O2(g) ® Na2CO3(s)

 

 

ANS:  E

 

42. Which of the following chemical equations does not correspond to a standard molar enthalpy of formation?

a.	Mg(s) + C(s) + 3/2 O2(g) ® MgCO3(s)
b.	C(s) + 1/2 O2(g) ® CO(g)
c.	N2(g) + O2(g) ® 2 NO(g)
d.	N2(g) + 2 O2(g) ® N2O4(g)
e.	H2(g) + 1/2 O2(g) ® H2O()

 

 

ANS:  C

 

43. Calculate D_fH° for sulfur dioxide given the thermochemical equations below.

	2 S(s) + 3 O2(g) ® 2 SO3(g)	DrH° = –791.5 kJ/mol-rxn
	2 SO2(g) + O2(g) ® 2 SO3(g)	DrH° = –197.9 kJ/mol-rxn

 

a.	–296.8 kJ/mol-rxn
b.	–395.7 kJ/mol-rxn
c.	–494.7 kJ/mol-rxn
d.	–593.6 kJ/mol-rxn
e.	–989.4 kJ/mol-rxn

 

 

ANS:  A

 

44. Calculate D_rH° for the combustion of ammonia,

4 NH₃(g) + 7 O₂(g) ® 4 NO₂(g) + 6 H₂O()

using standard molar enthalpies of formation.

 

	molecule	DfH° (kJ/mol-rxn)
	NH3(g)	–45.9
	NO2(g)	+33.1
	H2O()	–285.8

 

a.	+30.24 kJ/mol-rxn
b.	–206.9 kJ/mol-rxn
c.	–298.6 kJ/mol-rxn
d.	–1398.8 kJ/mol-rxn
e.	–1663.6 kJ/mol-rxn

 

 

ANS:  D

 

 

45. The standard enthalpy change for the combustion of 1 mole of propane is –2043.0 kJ.

C₃H₈(g) + 5 O₂(g) ® 3 CO₂(g) + 4 H₂O(g)

Calculate D_fH° for propane based on the following standard molar enthalpies of formation.

 

	molecule	DfH° (kJ/mol-rxn)
	CO2(g)	–393.5
	H2O(g)	–241.8

 

a.	–1407.7 kJ/mol-rxn
b.	+104.7 kJ/mol-rxn
c.	–104.7 kJ/mol-rxn
d.	–4190.7 kJ/mol-rxn
e.	+1407.7 kJ/mol-rxn

 

 

ANS:  C

 

46. The standard molar enthalpy of formation of NH₃(g) is –45.9 kJ/mol. What is the enthalpy change if 9.51 g N₂(g) and 1.96 g H₂(g) react to produce NH₃(g)?

a.	–10.3 kJ/mol-rxn
b.	–20.7 kJ/mol-rxn
c.	–29.8 kJ/mol-rxn
d.	–43.7 kJ/mol-rxn
e.	–65.6 kJ/mol-rxn

 

 

ANS:  C

 

SHORT ANSWER

 

47. In thermodynamics, a(n) ________ is defined as the object, or collection of objects, being studied. The surroundings include everything else.

 

ANS:

system

 

 

48. The heat required to convert a solid at its melting point to a liquid is called the heat of ________.

 

ANS:

fusion

 

 

49. Dry ice converts directly from a solid to a gas when heated. This process is called ________.

 

ANS:

sublimation

 

 

50. Why are you at greater risk from being burned by steam at 100 °C than from liquid water at the same temperature?

 

ANS:

At 100 °C, steam has approximately 40 kJ/mole more potential energy than liquid water at the same temperature.

 

 

51. Internal energy and enthalpy are state functions. What is meant by this statement?

 

ANS:

In any process, the change in internal energy or the change in enthalpy is independent of the path between the two states. These values depend only on the initial and final states.