Question 1

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. 
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.

Question 2

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

Accepted Answer

a.Standard state is the stable

Question 3

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 kJ 
A) -1.5 × 103 kJ 
B) -1.6× 103 kJ 
C) -4.4 × 103 kJ 
D) -4.7× 103 kJ 
E) -9.0× 103 kJ

Question 4

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 5

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 kJ 
A) 2.60 J 
B) 2.63 kJ 
C) 6.74 kJ 
D) 9.37 kJ 
E) 3.94×104 kJ

Question 6

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. 
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.

Question 7

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

Question 8

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

Question 9

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 10

Internal energy = _________ + ___________

Accepted Answer

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

Question 11

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/mol 
A) +41.0 kJ/mol 
B) -1567.4 kJ/mol 
C) 1567 kJ/mol 
D) -41.0 kJ/mol 
E) -763.7 kJ/mol

Question 12

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 13

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

Accepted Answer

A) True 
 B)False

Question 14

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  0. 
E) W > ΔU. 
A) W = ΔU. 
B) W = -ΔU. 
C) W > 0,ΔU  0. 
E) W > ΔU.

Question 15

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 J 
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 J

Question 16

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

Question 17

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

Question 18

Which of these is not a state function?

Accepted Answer

A) volume 
B) temperature 
C) pressure 
D) heat 
E) energy 
A) volume 
B) temperature 
C) pressure 
D) heat 
E) energy

Question 19

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/mol 
A) -520.9 kJ/mol 
B) -396.5 kJ/mol 
C) -384.9 kJ/mol 
D) -147.6 kJ/mol 
E) 24 kJ/mol

Question 20

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,indeterminate 
A) exothermic,positive 
B) exothermic,negative 
C) endothermic,positive 
D) endothermic,negative 
E) forbidden,indeterminate

Exam 5: Thermochemistry

The specific heat (capacity)is

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

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

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.

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.

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

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

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

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

Internal energy = _________ + ___________

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

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

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

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

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

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)

Which of these is not a state function?

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

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

Chemistry: the Central Science

Atoms Molecules and Ions

Stoichiometry Ratios of Combination

Reactions in Aqueous Solutions

Quantum Theory and the Electronic Structure of Atoms

Electron Configuration and the Periodic Table

Chemical Bonding I Basic Concepts

Chemical Bonding Ii Molecular Geometry and Bonding Theories

Gases

Intermolecular Forces and the Physical Properties of Liquids and Solids

Modern Materials

Physical Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Entropy Free Energy and Equilibrium

Electrochemistry

Nuclear Chemistry

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Metallurgy and the Chemistry of Metals

Nonmetallic Elements and Their Compounds

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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

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

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

Internal energy = _ + ___

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

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

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

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