Question 1

Use the ΔfH° and ΔrH° information provided to calculate ΔfH° for SO3(g): ΔfH° (kJ mol-1) 2SO2(g)+ O2(g)→ 2SO3(g)ΔrH° = -198 kJ
SO2(g) -297

Accepted Answer

A) -792 kJ mol-1 
B) -248 kJ mol-1 
C) -495 kJ mol-1 
D) -578 kJ mol-1 
E) -396 kJ mol-1 
A) -792 kJ mol-1 
B) -248 kJ mol-1 
C) -495 kJ mol-1 
D) -578 kJ mol-1 
E) -396 kJ mol-1 E

Question 2

According to the following reaction, how much energy is required to decompose 55.0 kg of Fe3O4? The molar mass of Fe3O4 is 231.55 g mol-1. Fe3O4(s)→ 3Fe(s)+ 2O2(g)ΔrH° = +1118 kJ

Accepted Answer

A) 1.10 × 106 kJ 
B) 2.38 × 102 kJ 
C) 2.66 × 105 kJ 
D) 1.12 × 103 kJ 
E) 3.44 × 104 kJ 
A) 1.10 × 106 kJ 
B) 2.38 × 102 kJ 
C) 2.66 × 105 kJ 
D) 1.12 × 103 kJ 
E) 3.44 × 104 kJ C

Question 3

Calculate the kinetic energy of a 150 g baseball moving at a speed of 39. m s-1 (87 mph).

Accepted Answer

A) 5.8 J 
B) 1.1 × 102 J 
C) 5.8 × 103 J 
D) 1.1 × 105 J 
A) 5.8 J 
B) 1.1 × 102 J 
C) 5.8 × 103 J 
D) 1.1 × 105 J B

Question 4

Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: 2H2O2(l)→ 2H2O(l)+ O2(g)ΔrH = -196 kJ
Calculate the value of q (kJ)in this exothermic reaction when 4.00 g of hydrogen peroxide decomposes at constant pressure?

Accepted Answer

A) -23.1 kJ mol-1 
B) -11.5 kJ mol-1 
C) -0.0217 kJ mol-1 
D) 1.44 kJ mol-1 
E) -2.31 × 104 kJ mol-1 
A) -23.1 kJ mol-1 
B) -11.5 kJ mol-1 
C) -0.0217 kJ mol-1 
D) 1.44 kJ mol-1 
E) -2.31 × 104 kJ mol-1

Question 5

Which of the following processes is exothermic?

Accepted Answer

A) the ionization of a lithium atom 
B) the breaking of a Cl-Cl bond 
C) the sublimation of dry ice (CO2(s)) 
D) the reaction associated with ΔfH° for an ionic compound 
E) All of the above processes are exothermic. 
A) the ionization of a lithium atom 
B) the breaking of a Cl-Cl bond 
C) the sublimation of dry ice (CO2(s)) 
D) the reaction associated with ΔfH° for an ionic compound 
E) All of the above processes are exothermic.

Question 6

Calculate the internal energy change, ΔrU, for the combustion of 9.467 g of L-alanine (C3H7NO2, molar mass = 89.094 g mol-1)if the combustion inside a bomb calorimeter, Ccal = 7.83 kJ °C-1, causes a temperature change from 24.7 °C to 46.1 °C.

Accepted Answer

A) -1.58 × 103 kJ mol-1 
B) 6.14 × 103 kJ mol-1 
C) -3.48 × 103 kJ mol-1 
D) -8.60 × 102 kJ mol-1 
E) 3.84 × 103 kJ mol-1 
A) -1.58 × 103 kJ mol-1 
B) 6.14 × 103 kJ mol-1 
C) -3.48 × 103 kJ mol-1 
D) -8.60 × 102 kJ mol-1 
E) 3.84 × 103 kJ mol-1

Question 7

A piece of uranium with a mass of 12.1 g and an initial temperature of 60.2 °C was placed inside a coffee cup calorimeter. The temperature of the water inside the calorimeter increased from 22.8 °C to 23.9 °C. The specific heat capacity of water is 4.184 J g-1 °C-1 and the specific heat capacity of uranium is 0.116 J g-1 °C-1. Calculate the mass of water contained inside the calorimeter.

Accepted Answer

A) 1.2 g 
B) 26 g 
C) 8.4 g 
D) 17 g 
E) 11 g 
A) 1.2 g 
B) 26 g 
C) 8.4 g 
D) 17 g 
E) 11 g

Question 8

Which of the following signs on q and w represent a system that is doing work on the surroundings as well as gaining heat from the surroundings?

Accepted Answer

A) q = +, w = - 
B) q = -, w = + 
C) q = +, w = + 
D) q = -, w = - 
E) None of these represent the system referenced above. 
A) q = +, w = - 
B) q = -, w = + 
C) q = +, w = + 
D) q = -, w = - 
E) None of these represent the system referenced above.

Question 9

Give the equation with the elements in MgSO4 in their standard state as the reactants and MgSO4 as the product.

Accepted Answer

Mg(s)+ 1/8

Question 10

Calculate the amount (mass)of acetaldehyde (C2H4O, molar mass = 44.0526 g mol-1)that causes a bomb calorimeter with a heat capacity of 12.91 kJ °C-1 to have a temperature increase from 27.8 °C to 41.7 °C. The $\Delta$rU for the combustion of acetaldehyde is -1166.9 kJ mol-1.

Accepted Answer

A) 6.77 g 
B) 8.67 g 
C) 4.29 g 
D) 7.30 g 
E) 5.55 g 
A) 6.77 g 
B) 8.67 g 
C) 4.29 g 
D) 7.30 g 
E) 5.55 g

Question 11

According to the following reaction, how much energy is evolved during the reaction of 32.5 g B2H6 and 72.5 g Cl2? The molar mass of B2H6 is 27.67 g mol-1. B2H6(g)+ 6Cl2(g)→ 2BCl3(g)+ 6HCl(g)ΔrH° = -1396 kJ

Accepted Answer

A) 1640 kJ 
B) 238 kJ 
C) 1430 kJ 
D) 3070 kJ 
E) 429 kJ 
A) 1640 kJ 
B) 238 kJ 
C) 1430 kJ 
D) 3070 kJ 
E) 429 kJ

Question 12

Calculate the final temperature of 6.84 g of praseodymium (specific heat capacity = 0.193 J g-1 °C-1)initially at 26.8 °C that releases 11.3 J of energy into the surroundings.

Accepted Answer

A) 14.3°C 
B) 18.2 °C 
C) 21.6 °C 
D) 23.8 °C 
E) 8.17 °C 
A) 14.3°C 
B) 18.2 °C 
C) 21.6 °C 
D) 23.8 °C 
E) 8.17 °C

Question 13

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g-1 °C-1)initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Accepted Answer

A) 34.1 °C 
B) 17.6 °C 
C) -34.1 °C 
D) -17.6 °C 
E) -8.70 °C 
A) 34.1 °C 
B) 17.6 °C 
C) -34.1 °C 
D) -17.6 °C 
E) -8.70 °C

Question 14

9.26 g of an unknown solid is dissolved in a coffee cup calorimeter that contains 62.0 mL of water. The measured temperature increased from 23.4 °C to 24.7 °C. The specific heat of water is 4.184 J g-1 °C-1, and assume the density of the solution is 1.00 g mL-1. Calculate the molecular weight of the unknown solid if the ΔrH was determined to be -2.51 kJ mol-1 via another experiment.

Accepted Answer

A) 69 g mol-1 
B) 48 g mol-1 
C) 76 g mol-1 
D) 184 g mol-1 
E) 93 g mol-1 
A) 69 g mol-1 
B) 48 g mol-1 
C) 76 g mol-1 
D) 184 g mol-1 
E) 93 g mol-1

Question 15

Energy that is associated with the position or composition of an object is called

Accepted Answer

A) kinetic energy. 
B) thermal energy. 
C) potential energy. 
D) chemical energy. 
A) kinetic energy. 
B) thermal energy. 
C) potential energy. 
D) chemical energy.

Question 16

Which of the following is TRUE if   U = -95 J?

Accepted Answer

A) The system is gaining 95 J, while the surroundings are losing 95 J. 
B) The system is losing 95 J, while the surroundings are gaining 95 J. 
C) Both the system and the surroundings are gaining 95 J. 
D) Both the system and the surroundings are losing 95 J. 
E) None of the above are true. 
A) The system is gaining 95 J, while the surroundings are losing 95 J. 
B) The system is losing 95 J, while the surroundings are gaining 95 J. 
C) Both the system and the surroundings are gaining 95 J. 
D) Both the system and the surroundings are losing 95 J. 
E) None of the above are true.

Question 17

Match the following.

-energy associated with the motion of an object
Match the following.

Accepted Answer

A) kinetic energy 
B) potential energy 
C) chemical energy 
D) thermal energy 
A) kinetic energy 
B) potential energy 
C) chemical energy 
D) thermal energy

Question 18

Using the following equation for the combustion of octane, calculate the amount of moles of oxygen that reacts with 100.0 g of octane. The molar mass of octane is 114.33 g mol-1. The molar mass of carbon dioxide is 44.0095 g mol-1. 2C8H18 + 25O2 → 16CO2 + 18 2O ΔrH° = -11018 kJ

Accepted Answer

A) 18.18 moles 
B) 6.997 moles 
C) 14.00 moles 
D) 8.000 moles 
E) 10.93 moles 
A) 18.18 moles 
B) 6.997 moles 
C) 14.00 moles 
D) 8.000 moles 
E) 10.93 moles

Question 19

Which of the following substances (with specific heat capacity provided)would show the greatest temperature change upon absorbing 100.0 J of heat?

Accepted Answer

A) 10.0 g Ag, CAg = 0.235 J g-1 °C-1 
B) 10.0 g H2O,   = 4.184 J g-1 °C-1 
C) 10.0 g ethanol, Cethanol = 2.42 J g-1 °C-1 
D) 10.0 g Fe, CFe = 0.449 J g-1 °C-1 
E) 10.0 g Au, CAu = 0.128 J g-1 °C-1 
A) 10.0 g Ag, CAg = 0.235 J g-1 °C-1 
B) 10.0 g H2O,   = 4.184 J g-1 °C-1 
C) 10.0 g ethanol, Cethanol = 2.42 J g-1 °C-1 
D) 10.0 g Fe, CFe = 0.449 J g-1 °C-1 
E) 10.0 g Au, CAu = 0.128 J g-1 °C-1

Question 20

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

Accepted Answer

The book starts out with a cer

Exam 6: Thermochemistry

Use the ΔfH° and ΔrH° information provided to calculate ΔfH° for SO3(g): ΔfH° (kJ mol-1) 2SO2(g)+ O2(g)→ 2SO3(g)ΔrH° = -198 kJ SO2(g) -297

According to the following reaction, how much energy is required to decompose 55.0 kg of Fe3O4? The molar mass of Fe3O4 is 231.55 g mol-1. Fe3O4(s)→ 3Fe(s)+ 2O2(g)ΔrH° = +1118 kJ

Calculate the kinetic energy of a 150 g baseball moving at a speed of 39. m s-1 (87 mph).

Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: 2H2O2(l)→ 2H2O(l)+ O2(g)ΔrH = -196 kJ Calculate the value of q (kJ)in this exothermic reaction when 4.00 g of hydrogen peroxide decomposes at constant pressure?

Which of the following processes is exothermic?

Calculate the internal energy change, ΔrU, for the combustion of 9.467 g of L-alanine (C3H7NO2, molar mass = 89.094 g mol-1)if the combustion inside a bomb calorimeter, Ccal = 7.83 kJ °C-1, causes a temperature change from 24.7 °C to 46.1 °C.

Which of the following signs on q and w represent a system that is doing work on the surroundings as well as gaining heat from the surroundings?

Give the equation with the elements in MgSO4 in their standard state as the reactants and MgSO4 as the product.

Calculate the amount (mass)of acetaldehyde (C2H4O, molar mass = 44.0526 g mol-1)that causes a bomb calorimeter with a heat capacity of 12.91 kJ °C-1 to have a temperature increase from 27.8 °C to 41.7 °C. The Δ\DeltaΔ rU for the combustion of acetaldehyde is -1166.9 kJ mol-1.

According to the following reaction, how much energy is evolved during the reaction of 32.5 g B2H6 and 72.5 g Cl2? The molar mass of B2H6 is 27.67 g mol-1. B2H6(g)+ 6Cl2(g)→ 2BCl3(g)+ 6HCl(g)ΔrH° = -1396 kJ

Calculate the final temperature of 6.84 g of praseodymium (specific heat capacity = 0.193 J g-1 °C-1)initially at 26.8 °C that releases 11.3 J of energy into the surroundings.

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g-1 °C-1)initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Energy that is associated with the position or composition of an object is called

Which of the following is TRUE if U = -95 J?

Match the following. -energy associated with the motion of an object Match the following.

Using the following equation for the combustion of octane, calculate the amount of moles of oxygen that reacts with 100.0 g of octane. The molar mass of octane is 114.33 g mol-1. The molar mass of carbon dioxide is 44.0095 g mol-1. 2C8H18 + 25O2 → 16CO2 + 18 2O ΔrH° = -11018 kJ

Which of the following substances (with specific heat capacity provided)would show the greatest temperature change upon absorbing 100.0 J of heat?

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

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Use the Δ_fH° and Δ_rH°information provided to calculate Δ_fH° for SO₃(g): Δ_fH°(kJ mol^-1₎ 2SO₂(g)+ O₂(g)→ 2SO₃(g)Δ_rH°= -198 kJ SO₂(g) -297

According to the following reaction, how much energy is required to decompose 55.0 kg of Fe₃O₄? The molar mass of Fe₃O₄is 231.55 g mol^-1. Fe₃O₄(s)→ 3Fe(s)+ 2O₂(g)Δ_rH°= +1118 kJ

Calculate the kinetic energy of a 150 g baseball moving at a speed of 39. m s^-1 (87 mph).

Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: 2H₂O₂(l)→ 2H₂O(l)+ O₂(g)Δ_rH = -196 kJ Calculate the value of q (kJ)in this exothermic reaction when 4.00 g of hydrogen peroxide decomposes at constant pressure?

Calculate the internal energy change, Δ_rU, for the combustion of 9.467 g of L-alanine (C₃H₇NO₂, molar mass = 89.094 g mol^-1)if the combustion inside a bomb calorimeter, C_cal = 7.83 kJ °C^-1, causes a temperature change from 24.7 °C to 46.1 °C.

Give the equation with the elements in MgSO₄ in their standard state as the reactants and MgSO₄ as the product.

Calculate the amount (mass)of acetaldehyde (C₂H₄O, molar mass = 44.0526 g mol^-1)that causes a bomb calorimeter with a heat capacity of 12.91 kJ °C^-1 to have a temperature increase from 27.8 °C to 41.7 °C. The $\Delta$ _rU for the combustion of acetaldehyde is -1166.9 kJ mol^-1.

According to the following reaction, how much energy is evolved during the reaction of 32.5 g B₂H₆ and 72.5 g Cl₂? The molar mass of B₂H₆is 27.67 g mol^-1. B₂H₆(g)+ 6Cl₂(g)→ 2BCl₃(g)+ 6HCl(g)Δ_rH°= -1396 kJ

Calculate the final temperature of 6.84 g of praseodymium (specific heat capacity = 0.193 J g^-1 °C^-1)initially at 26.8 °C that releases 11.3 J of energy into the surroundings.

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g^-1 °C^-1)initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Using the following equation for the combustion of octane, calculate the amount of moles of oxygen that reacts with 100.0 g of octane. The molar mass of octane is 114.33 g mol^-1. The molar mass of carbon dioxide is 44.0095 g mol^-1. 2C₈H₁₈ + 25O₂ → 16CO₂ + 18 ₂O Δ_rH°= -11018 kJ