Question 1

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.800 atm. The value of w, in J, is

Accepted Answer

A)  −4.0 J.
B)  4.0 J.
C)  −405 J.
D)  405 J.
E)  4.05 × 10 3 J.F) A) and D)
G) A) and E)

Question 2

Use the following data to calculate the standard heat (enthalpy)  of formation, ΔHf°, of manganese(IV)  oxide, MnO2 (s) . 2MnO2(s)  → 2MnO(s)  + O2(g)  ΔH = 264 kJ
MnO2(s)  + Mn(s)  → 2MnO(s)  ΔH = −240 kJ

Accepted Answer

A)  −504 kJ
B)  −372 kJ
C)  −24 kJ
D)  24 kJ
E)  504 kJF) D) and E)
G) A) and D)

Question 3

Calcium hydroxide, which reacts with carbon dioxide to form calcium carbonate, was used by the ancient Romans as mortar in stone structures. The reaction for this process is Ca(OH) 2(s)  + CO2(g)  → CaCO3(s)  + H2O(g)  ΔH = −69.1 kJ
What is the enthalpy change if 3.8 mol of calcium carbonate is formed?

Accepted Answer

A)  −18 kJ
B)  −69 kJ
C)  −73 kJ
D)  −260 kJ
E)  None of these choices are correct.F) C) and D)
G) A) and C)

Question 4

Which of the following is not a state function?

Accepted Answer

A)  Internal energy
B)  Volume
C)  Work
D)  Pressure
E)  EnthalpyF) A) and D)
G) B) and E)

Question 5

15.0 g of ice cubes at 0.0°C are combined with 150 g of liquid water at 70.0°C in a coffee cup calorimeter. Calculate the final temperature reached, assuming no heat loss or gain from the surroundings. (Data: specific heat capacity of H2O(l) , c = 4.18 J/g·°C; H2O(s)  → H2O(l)  ΔH = 6.02 kJ/mol)

Accepted Answer

A)  0.0
B)  10.6
C)  30.7
D)  43.2
E)  56.4F) A) and B)
G) C) and D)

Question 6

For all processes, both q and ΔE will have the same sign.

Accepted Answer

A) True 
 B)False

Question 7

Combustion of a hydrocarbon will release more energy than combustion of an equal mass of carbohydrate because

Accepted Answer

A)  the C-O and O-H single bonds in carbohydrates are weak.
B)  carbohydrates contain C-O and O-H bonds and hydrocarbons do not.
C)  the total energy of the C-C and C-H bonds in hydrocarbons is greater than the total energy of the C=O and O-H bonds in the combustion products (carbon dioxide and water) .
D)  the total energy of the bonds in hydrocarbons is greater than the energy of the bonds in carbohydrates.
E)  hydrocarbons have higher molar masses than carbohydrates.F) A) and B)
G) D) and E)

Question 8

Nitric acid, which is among the top 15 chemicals produced in the United States, was first prepared over 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter)  with sulfuric acid and collecting the vapors produced. Calculate ΔH°rxn for this reaction. ΔH°f [NaNO3(s) ] = −467.8 kJ/mol; ΔH°f [NaHSO4(s) ] = −1125.5 kJ/mol; ΔH°f [H2SO4(l)  = −814.0 kJ/mol; ΔH°f [HNO3(g) ] = −135.1 kJ/mol
NaNO3(s)  + H2SO4(l)  → NaHSO4(s)  + HNO3(g)

Accepted Answer

A)  −644.2 kJ
B)  −291.4 kJ
C)  −21.2 kJ
D)  21.2 kJ
E)  644.2 kJF) A) and B)
G) A) and C)

Question 9

Which one of the following is not a correct formation reaction? (products are correct)

Accepted Answer

A)  H 2( g) + O( g) → H 2O( l) 
B)  ½H 2( g) + ½Cl 2( g) → HCl( g) 
C)  6C(graphite) + 3H 2( g) → C 6H 6( l) 
D)  C(graphite) → C(diamond) 
E)  6C(graphite) + 6H 2( g) + 3O 2( g) → C 6H 12O 6( s) F) None of the above
G) A) and B)

Question 10

The highly exothermic thermite reaction, in which aluminum reduces iron(III)  oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s)  + Fe2O3(s)  → 2Fe(s)  + Al2O3(s)  ΔH = −850 kJ
What mass of iron is formed when 725 kJ of heat are released?

Accepted Answer

A)  47 g
B)  65 g
C)  95 g
D)  112 g
E)  130 gF) A) and D)
G) C) and E)

Question 11

A Snickers® candy bar contains 280 Calories, of which the fat content accounts for 120 Calories. What is the energy of the fat content, in kJ?

Accepted Answer

A)  5.0 × 10 −1 kJ
B)  29 kJ
C)  5.0 × 10 2 kJ
D)  1.2 × 10 3 kJ
E)  5.0 × 10 5 kJF) B) and D)
G) A) and D)

Exam 6: Thermochemistry: Energy Flow and Chemical Change

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.800 atm. The value of w, in J, is

Correct Answer
verified

Correct Answer
verified

Which of the following is not a state function?

Correct Answer
verified

For all processes, both q and ΔE will have the same sign.

Correct Answer
verified

Use the following data to calculate the standard heat (enthalpy) of formation, ΔH_f°, of manganese(IV) oxide, MnO₂(s) . 2MnO₂(s) → 2MnO(s) + O₂(g) ΔH = 264 kJ MnO₂(s) + Mn(s) → 2MnO(s) ΔH = −240 kJ

Correct Answer
verified

A Snickers^® candy bar contains 280 Calories, of which the fat content accounts for 120 Calories. What is the energy of the fat content, in kJ?

Correct Answer
verified

Combustion of a hydrocarbon will release more energy than combustion of an equal mass of carbohydrate because

Correct Answer
verified

Which one of the following is not a correct formation reaction? (products are correct)

Correct Answer
verified

Correct Answer
verified

The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH = −850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct Answer
verified

Correct Answer
verified

Exam 6: Thermochemistry: Energy Flow and Chemical Change

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.800 atm. The value of w, in J, is

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following is not a state function?

Correct AnswerverifiedShow Answer

For all processes, both q and ΔE will have the same sign.

Correct AnswerverifiedShow Answer

Use the following data to calculate the standard heat (enthalpy) of formation, ΔHf°, of manganese(IV) oxide, MnO2 (s) . 2MnO2(s) → 2MnO(s) + O2(g) ΔH = 264 kJ MnO2(s) + Mn(s) → 2MnO(s) ΔH = −240 kJ

Correct AnswerverifiedShow Answer

A Snickers® candy bar contains 280 Calories, of which the fat content accounts for 120 Calories. What is the energy of the fat content, in kJ?

Correct AnswerverifiedShow Answer

Combustion of a hydrocarbon will release more energy than combustion of an equal mass of carbohydrate because

Correct AnswerverifiedShow Answer

Which one of the following is not a correct formation reaction? (products are correct)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s) ΔH = −850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Use the following data to calculate the standard heat (enthalpy) of formation, ΔH_f°, of manganese(IV) oxide, MnO₂(s) . 2MnO₂(s) → 2MnO(s) + O₂(g) ΔH = 264 kJ MnO₂(s) + Mn(s) → 2MnO(s) ΔH = −240 kJ

Correct Answer
verified

A Snickers^® candy bar contains 280 Calories, of which the fat content accounts for 120 Calories. What is the energy of the fat content, in kJ?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH = −850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct Answer
verified

Correct Answer
verified