Question 1

What is q if 28.6 g of water is heated from 22.0°C to 78.3°C? The specific heat of water is 4.184 J/g·°C.

Accepted Answer

A)  2.60 J
B)  2.63 kJ
C)  6.74 kJ
D)  9.37 kJ
E)  3.94×104 kJF) None of the above
G) A) and E)

Question 2

Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l) .What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f(kJ/mol) 
B2O3(s) -1273.5
B5H9(s) +73.2
H2O(l) -285.8

Accepted Answer

A)  -1.5 × 103 kJ
B)  -1.6× 103 kJ
C)  -4.4 × 103 kJ
D)  -4.7× 103 kJ
E)  -9.0× 103 kJF) B) and D)
G) All of the above

Question 3

A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm.What is the work (W) done by the system? (1 L·atm = 101.3 J)

Accepted Answer

A)  1.00 J
B)  2.00 J
C)  1.01 × 102 J
D)  1.01 × 105 J
E)  3.00 JF) B) and D)
G) A) and B)

Question 4

Using Hess's law,what is the standard enthalpy of formation,ΔH°f of manganese(II) oxide,MnO(s) ? 2MnO2(s) → 2MnO(s) +O2(g) ΔH°rxn = +272.0 kJ/mol
MnO2(s) + Mn(s) → 2MnO(s) ΔH°rxn = -248.9 kJ/mol

Accepted Answer

A)  -520.9 kJ/mol
B)  -396.5 kJ/mol
C)  -384.9 kJ/mol
D)  -147.6 kJ/mol
E)  24 kJ/molF) C) and E)
G) None of the above

Question 5

For the reaction: 2A + B2 → 2AB ΔH = +50.0 kJ.

Accepted Answer

A)  The reaction is endothermic.
B)  Heat is released to the surroundings.
C)  The standard enthalpy of formation for AB is 50.0 kJ.
D)  The bond energy for each A-B bond is 50.0 kJ.
E)  The molecule AB contains less energy than A or B2.F) A) and C)
G) C) and E)

Question 6

Complete the sentence: When heat is transferred to the system,the process is said to be ____________,and the sign of q is __________.

Accepted Answer

A)  exothermic,positive
B)  exothermic,negative
C)  endothermic,positive
D)  endothermic,negative
E)  forbidden,indeterminateF) C) and E)
G) A) and C)

Question 7

The sign of q when heat is released by the system is _______________.

Accepted Answer

The answer of The sign of q when heat is...

Question 8

Based on the following thermochemical equations,what is the heat of vaporization of titanium(IV) chloride? Ti(s) + 2 Cl2(g) → TiCl4(l) 
ΔH = -804.2 kJ/mol
TiCl4(g) → 2 Cl2(g) + Ti(s) 
ΔH = 763.2 kJ/mol

Accepted Answer

A)  +41.0 kJ/mol
B)  -1567.4 kJ/mol
C)  1567 kJ/mol
D)  -41.0 kJ/mol
E)  -763.7 kJ/molF) None of the above
G) A) and B)

Question 9

A system which does work on the surroundings with no heat change has

Accepted Answer

A)  W = ΔU.
B)  W = -ΔU.
C)  W > 0,ΔU 
D)  W  0.
E)  W > ΔU.F) None of the above
G) A) and E)

Question 10

What is ΔH°rxn for the following reaction? 2H2O2(l) → 2H2O(l) + O2(g) 
ΔH°f(H2O(l) ) = -285.8 kJ/mol,ΔH°f(H2O2(l) ) = -187.6 kJ/mol

Accepted Answer

A)  -196.4 kJ/mol
B)  98.2 kJ/mol
C)  -98.2 kJ/mol
D)  -473.4 kJ/mol
E)  -946.8 kJ/molF) B) and E)
G) A) and B)

Question 11

The sign of w when work is done on the system by the surroundings is ___________.

Accepted Answer

The answer of The sign of w when work is...

Question 12

Internal energy = _________ + ___________

Accepted Answer

The answer of Internal energy = _________ + ___________...

Question 13

How many joules are in 1.20 ×103 calories? (1 cal = 4.184 J)

Accepted Answer

A)  8.33 × 10-4 J
B)  3.49 × 10-3 J
C)  2.39 × 10-1 J
D)  2.86 × 102 J
E)  5.02 × 103 JF) C) and D)
G) B) and E)

Question 14

The specific heat (capacity) is

Accepted Answer

A)  amount of energy needed to change 1 g of a substance by 1°C.
B)  amount of energy needed to change 1 mol of a substance by 1°C.
C)  amount of energy required to melt 1 g of substance.
D)  amount of substance that is heated by 1°C.
E)  the temperature increase,in K,associated with heating 1 g of a substance for 1 minute.F) C) and E)
G) C) and D)

Question 15

Octane (C8H18) undergoes combustion according to the following thermochemical equation. 2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH°rxn = -1.0940 × 104kJ/mol
What is the standard enthalpy of formation of liquid octane?
ΔH°f(CO2(g) ) = -393.5 kJ/mol and ΔH°f(H2O(l) ) = -285.8 kJ/mol

Accepted Answer

A)  -250 kJ/mol
B)  -10,940.kJ/mol
C)  -2188 kJ/mol
D)  -495 kJ/mol
E)  495 kJ/molF) C) and D)
G) A) and B)

Question 16

a.Explain fully what is meant by the term "state function."
b.(i)Give two examples of thermodynamic quantities which are state functions.
(ii)Give two examples of thermodynamic quantities which are not state functions.

Accepted Answer

a.A state function depends onl...

Question 17

All elements in their standard state have an enthalpy of formation equal to zero.

Accepted Answer

A) True 
 B)False

Question 18

Clearly state the thermodynamic standard state of a.an element or compound.
b.a solute.

Accepted Answer

a.Standard state is the stable...

Question 19

The bond enthalpy of the Br-Cl bond is equal to ΔH°rxn for the following reaction. BrCl(g) → Br(g) + Cl(g) 
Using the following data,what is the bond enthalpy of the Br-Cl bond?
Br2(l) → Br2(g) ΔH°rxn = 30.91 kJ/mol
Br2(g) → 2Br(g) ΔH°rxn = 192.9 kJ/mol
Cl2(g) → 2Cl(g) ΔH°rxn = 243.4 kJ/mol
Br2(l) + Cl2(g) → 2BrCl(g) ΔH°rxn = 29.2 kJ/mol

Accepted Answer

A)  219.0 kJ/mol
B)  203.5 kJ/mol
C)  14.6 kJ/mol
D)  438.0 kJ/mol
E)  407.0 kJ/molF) B) and D)
G) A) and B)

Question 20

Which of these is not a state function?

Accepted Answer

A)  volume
B)  temperature
C)  pressure
D)  heat
E)  energyF) All of the above
G) B) and E)

Exam 5: Thermochemistry

What is q if 28.6 g of water is heated from 22.0°C to 78.3°C? The specific heat of water is 4.184 J/g·°C.

Correct Answer
verified

All elements in their standard state have an enthalpy of formation equal to zero.

Correct Answer
verified

Correct Answer
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Based on the following thermochemical equations,what is the heat of vaporization of titanium(IV) chloride? Ti(s) + 2 Cl₂(g) → TiCl₄(l) ΔH = -804.2 kJ/mol TiCl₄(g) → 2 Cl₂(g) + Ti(s) ΔH = 763.2 kJ/mol

Correct Answer
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The sign of w when work is done on the system by the surroundings is ___________.

Correct Answer
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The sign of q when heat is released by the system is _______________.

Correct Answer
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What is ΔH°_rxn for the following reaction? 2H₂O₂(l) → 2H₂O(l) + O₂(g) ΔH°_f(H₂O(l) ) = -285.8 kJ/mol,ΔH°_f(H₂O₂(l) ) = -187.6 kJ/mol

Correct Answer
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Which of these is not a state function?

Correct Answer
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Clearly state the thermodynamic standard state of a.an element or compound. b.a solute.

Correct Answer
verified
a.Standard state is the stable...
View Answer

A system which does work on the surroundings with no heat change has

Correct Answer
verified

Using Hess's law,what is the standard enthalpy of formation,ΔH°_f of manganese(II) oxide,MnO(s) ? 2MnO₂(s) → 2MnO(s) +O₂(g) ΔH°_rxn = +272.0 kJ/mol MnO₂(s) + Mn(s) → 2MnO(s) ΔH°_rxn = -248.9 kJ/mol

Correct Answer
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A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm.What is the work (W) done by the system? (1 L·atm = 101.3 J)

Correct Answer
verified

Correct Answer
verified

For the reaction: 2A + B₂ → 2AB ΔH = +50.0 kJ.

Correct Answer
verified

How many joules are in 1.20 ×10³ calories? (1 cal = 4.184 J)

Correct Answer
verified

Complete the sentence: When heat is transferred to the system,the process is said to be __,and the sign of q is .

Correct Answer
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Internal energy = _ + ___

Correct Answer
verified

The specific heat (capacity) is

Correct Answer
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Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) .What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f(kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
verified

a.Explain fully what is meant by the term "state function." b.(i)Give two examples of thermodynamic quantities which are state functions. (ii)Give two examples of thermodynamic quantities which are not state functions.

Correct Answer
verified
a.A state function depends onl...
View Answer

Exam 5: Thermochemistry

What is q if 28.6 g of water is heated from 22.0°C to 78.3°C? The specific heat of water is 4.184 J/g·°C.

Correct AnswerverifiedShow Answer

All elements in their standard state have an enthalpy of formation equal to zero.

Correct AnswerverifiedShow Answer

Octane (C8H18) undergoes combustion according to the following thermochemical equation. 2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH°rxn = -1.0940 × 104kJ/mol What is the standard enthalpy of formation of liquid octane? ΔH°f(CO2(g) ) = -393.5 kJ/mol and ΔH°f(H2O(l) ) = -285.8 kJ/mol

Correct AnswerverifiedShow Answer

Based on the following thermochemical equations,what is the heat of vaporization of titanium(IV) chloride? Ti(s) + 2 Cl2(g) → TiCl4(l) ΔH = -804.2 kJ/mol TiCl4(g) → 2 Cl2(g) + Ti(s) ΔH = 763.2 kJ/mol

Correct AnswerverifiedShow Answer

The sign of w when work is done on the system by the surroundings is ___________.

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The sign of q when heat is released by the system is _______________.

Correct AnswerverifiedShow Answer

What is ΔH°rxn for the following reaction? 2H2O2(l) → 2H2O(l) + O2(g) ΔH°f(H2O(l) ) = -285.8 kJ/mol,ΔH°f(H2O2(l) ) = -187.6 kJ/mol

Correct AnswerverifiedShow Answer

Which of these is not a state function?

Correct AnswerverifiedShow Answer

Clearly state the thermodynamic standard state of a.an element or compound. b.a solute.

Correct Answerverifieda.Standard state is the stable...View AnswerShow Answer

A system which does work on the surroundings with no heat change has

Correct AnswerverifiedShow Answer

Using Hess's law,what is the standard enthalpy of formation,ΔH°f of manganese(II) oxide,MnO(s) ? 2MnO2(s) → 2MnO(s) +O2(g) ΔH°rxn = +272.0 kJ/mol MnO2(s) + Mn(s) → 2MnO(s) ΔH°rxn = -248.9 kJ/mol

Correct AnswerverifiedShow Answer

A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm.What is the work (W) done by the system? (1 L·atm = 101.3 J)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

For the reaction: 2A + B2 → 2AB ΔH = +50.0 kJ.

Correct AnswerverifiedShow Answer

How many joules are in 1.20 ×103 calories? (1 cal = 4.184 J)

Correct AnswerverifiedShow Answer

Complete the sentence: When heat is transferred to the system,the process is said to be ____________,and the sign of q is __________.

Correct AnswerverifiedShow Answer

Internal energy = _________ + ___________

Correct AnswerverifiedShow Answer

The specific heat (capacity) is

Correct AnswerverifiedShow Answer

Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l) .What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f(kJ/mol) B2O3(s) -1273.5 B5H9(s) +73.2 H2O(l) -285.8

Correct AnswerverifiedShow Answer

a.Explain fully what is meant by the term "state function." b.(i)Give two examples of thermodynamic quantities which are state functions. (ii)Give two examples of thermodynamic quantities which are not state functions.

Correct Answerverifieda.A state function depends onl...View AnswerShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Based on the following thermochemical equations,what is the heat of vaporization of titanium(IV) chloride? Ti(s) + 2 Cl₂(g) → TiCl₄(l) ΔH = -804.2 kJ/mol TiCl₄(g) → 2 Cl₂(g) + Ti(s) ΔH = 763.2 kJ/mol

Correct Answer
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Correct Answer
verified

Correct Answer
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What is ΔH°_rxn for the following reaction? 2H₂O₂(l) → 2H₂O(l) + O₂(g) ΔH°_f(H₂O(l) ) = -285.8 kJ/mol,ΔH°_f(H₂O₂(l) ) = -187.6 kJ/mol

Correct Answer
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Correct Answer
verified

Correct Answer
verified
a.Standard state is the stable...
View Answer

Correct Answer
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Using Hess's law,what is the standard enthalpy of formation,ΔH°_f of manganese(II) oxide,MnO(s) ? 2MnO₂(s) → 2MnO(s) +O₂(g) ΔH°_rxn = +272.0 kJ/mol MnO₂(s) + Mn(s) → 2MnO(s) ΔH°_rxn = -248.9 kJ/mol

Correct Answer
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Correct Answer
verified

Correct Answer
verified

For the reaction: 2A + B₂ → 2AB ΔH = +50.0 kJ.

Correct Answer
verified

How many joules are in 1.20 ×10³ calories? (1 cal = 4.184 J)

Correct Answer
verified

Complete the sentence: When heat is transferred to the system,the process is said to be __,and the sign of q is .

Correct Answer
verified

Internal energy = _ + ___

Correct Answer
verified

Correct Answer
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Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) .What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f(kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
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Correct Answer
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a.A state function depends onl...
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