Question 1

For all processes, both q and F1F1F1S1F1F1F10E will have the same sign.

Accepted Answer

A) True 
 B)False

Question 2

The reaction
2NaOH(aq) + H2SO4(aq) F1F1F1S1F1F1F10 Na2SO4(aq) + 2H2O(l)
was studied in a coffee cup calorimeter. 100. mL portions of 1.00 M aqueous NaOH and H2SO4, each at 24.0°C, were mixed. The maximum temperature achieved was 30.6°C. Neglect the heat capacity of the cup and the thermometer, and assume that the solution of products has a density of exactly 1 g/mL and a specific heat capacity of 4.18 J/(g·K).
a. Calculate the heat of reaction, q, in J.
b. Calculate F1F1F1S1F1F1F10H, the heat (enthalpy) of reaction, in kJ/mol of Na2SO4 produced.

Accepted Answer

a. 5.5 × 1

Question 3

Which of the following is not a state function?

Accepted Answer

A)  internal energy 
B)  volume 
C)  work 
D)  pressure 
E)  enthalpy 
A)  internal energy 
B)  volume 
C)  work 
D)  pressure 
E)  enthalpy

Question 4

The combustion of glucose (C6H12O6) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

Accepted Answer

A)  223.5 kcal 
B)  335.3 kcal 
C)  1402 kcal 
D)  2012 kcal 
E)  5858 kcal 
A)  223.5 kcal 
B)  335.3 kcal 
C)  1402 kcal 
D)  2012 kcal 
E)  5858 kcal

Question 5

An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH3(g) + 5O2(g) F1F1F1S1F1F1F10 4NO(g) + 6H2O(g)
Calculate F1F1F1S1F1F1F10H°rxn for this reaction.
F1F1F1S1F1F1F10H°f [NH3(g)] = -45.9 kJ/mol; F1F1F1S1F1F1F10H°f [NO(g)] = 90.3 kJ/mol; F1F1F1S1F1F1F10H°f [H2O(g)] = -241.8 kJ/mol

Accepted Answer

A)  -906.0 kJ 
B)  -197.4 kJ 
C)  -105.6 kJ 
D)  197.4 kJ 
E)  906.0 kJ 
A)  -906.0 kJ 
B)  -197.4 kJ 
C)  -105.6 kJ 
D)  197.4 kJ 
E)  906.0 kJ

Question 6

Use Hess's Law to calculate the enthalpy change for the reaction 
WO3(s) + 3H2(g) F1F1F1S1F1F1F10 W(s) + 3H2O(g)
From the following data:
2W(s) + 3O2(g) F1F1F1S1F1F1F10 2WO3(s) F1F1F1S1F1F1F10H = -1685.4 kJ
2H2(g) + O2(g) F1F1F1S1F1F1F10 2H2O(g) F1F1F1S1F1F1F10H = -477.84 kJ

Accepted Answer

A)  125.9 kJ 
B)  252.9 kJ 
C)  364.9 kJ 
D)  1207.6 kJ 
E)  none of the above 
A)  125.9 kJ 
B)  252.9 kJ 
C)  364.9 kJ 
D)  1207.6 kJ 
E)  none of the above

Question 7

The standard state of a substance in aqueous solution is a 1 M solution.

Accepted Answer

A) True 
 B)False

Question 8

Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories?

Accepted Answer

A)  1.92 × 10-1 kcal 
B)  1.92 × 102 kcal 
C)  3.36 × 103 kcal 
D)  1.92 × 105 kcal 
E)  3.36 × 106 kcal 
A)  1.92 × 10-1 kcal 
B)  1.92 × 102 kcal 
C)  3.36 × 103 kcal 
D)  1.92 × 105 kcal 
E)  3.36 × 106 kcal

Question 9

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g·K)

Accepted Answer

A)  39.6°C 
B)  40.8°C 
C)  61.0°C 
D)  79.2°C 
E)  82.4°C 
A)  39.6°C 
B)  40.8°C 
C)  61.0°C 
D)  79.2°C 
E)  82.4°C

Question 10

Your favorite candy bar, Gummy Beakers, contains 1.2 × 106 J of energy while your favorite soft drink, Bolt, contains 6.7 × 105 J. If you eat two packs of Gummy Beakers a day and drink 3 cans of Bolt, what percent of your 2000 Calorie daily food intake is left for broccoli, beans, beef, etc.?

Accepted Answer

A)  53% 
B)  47% 
C)  27% 
D)  11% 
E)  0% 
A)  53% 
B)  47% 
C)  27% 
D)  11% 
E)  0%

Question 11

a. State Hess's Law.
b. Use the F1F1F1S1F1F1F10H° data given below to calculate F1F1F1S1F1F1F10H° for the reaction:

Accepted Answer

a. The enthalpy change for an

Question 12

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) F1F1F1S1F1F1F10 CaCO3(s) + H2O(g) F1F1F1S1F1F1F10H = -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 the above 
A)  -18 kJ 
B)  -69 kJ 
C)  -73 kJ 
D)  -260 kJ 
E)  none of the above

Question 13

The standard heat (enthalpy) of formation of graphite is zero.

Accepted Answer

A) True 
 B)False

Question 14

Which one of the following equations represents the formation reaction of CH3OH(l)?

Accepted Answer

A)  C(g) + 2H2(g) +   O2 (g) F1F1F1S1F1F1F10 CH3OH(l) 
B)  C(g) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
C)  C(graphite) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
D)  C(diamond) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
E)  C(graphite) + 2H2(g) +   O2(g) F1F1F1S1F1F1F10 CH3OH(l) 
A)  C(g) + 2H2(g) +   O2 (g) F1F1F1S1F1F1F10 CH3OH(l) 
B)  C(g) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
C)  C(graphite) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
D)  C(diamond) + 4H(g) + O(g) F1F1F1S1F1F1F10 CH3OH(l) 
E)  C(graphite) + 2H2(g) +   O2(g) F1F1F1S1F1F1F10 CH3OH(l)

Question 15

a. Write a balanced equation for the combustion of benzene, C6H6(l) in oxygen.
b. The standard heat of combustion of benzene is -3271 kJ/mol. Calculate its standard heat of formation, F1F1F1S1F1F1F10H°f , given the data:
F1F1F1S1F1F1F10H°f [CO2(g)] = -394 kJ; F1F1F1S1F1F1F10H°f [H2O(l)] = -286 kJ

Accepted Answer

a. C₆H₆(l) + 7.5O₂(g) F1F1F1S1F1

Question 16

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam). Its specific heat capacity is 1.74 J/(g·K). If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?

Accepted Answer

A)  -22.7°C 
B)  36.7°C 
C)  42.7°C 
D)  62.7°C 
E)  none of the above 
A)  -22.7°C 
B)  36.7°C 
C)  42.7°C 
D)  62.7°C 
E)  none of the above

Question 17

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Accepted Answer

A)  32.7 kJ 
B)  46.5 kJ 
C)  75.9 kJ 
D)  82.8 kJ 
E)  89.7 kJ 
A)  32.7 kJ 
B)  46.5 kJ 
C)  75.9 kJ 
D)  82.8 kJ 
E)  89.7 kJ

Question 18

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C?

Accepted Answer

A)  35°C 
B)  42°C 
C)  53°C 
D)  58°C 
E)  70°C 
A)  35°C 
B)  42°C 
C)  53°C 
D)  58°C 
E)  70°C

Question 19

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

Accepted Answer

A)  H2(g) + O(g) F1F1F1S1F1F1F10 H2O(l) 
B)    H2(g) +   Cl2(g) F1F1F1S1F1F1F10 HCl(g) 
C)  6C(graphite) + 3H2(g) F1F1F1S1F1F1F10 C6H6(l) 
D)  C(graphite) F1F1F1S1F1F1F10 C(diamond) 
E)  6C(graphite) + 6H2(g) + 3O2(g) F1F1F1S1F1F1F10 C6H12O6(s) 
A)  H2(g) + O(g) F1F1F1S1F1F1F10 H2O(l) 
B)    H2(g) +   Cl2(g) F1F1F1S1F1F1F10 HCl(g) 
C)  6C(graphite) + 3H2(g) F1F1F1S1F1F1F10 C6H6(l) 
D)  C(graphite) F1F1F1S1F1F1F10 C(diamond) 
E)  6C(graphite) + 6H2(g) + 3O2(g) F1F1F1S1F1F1F10 C6H12O6(s)

Question 20

Calculate the F1F1F1S1F1F1F10H°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. F1F1F1S1F1F1F10H°f [CaCO3(s)] = -1206.9 kJ/mol; F1F1F1S1F1F1F10H°f [CaO(s)] = -635.1 kJ/mol; F1F1F1S1F1F1F10H°f [CO2(g)] = -393.5 kJ/mol
CaCO3(s) F1F1F1S1F1F1F10 CaO(s) + CO2(g)

Accepted Answer

A)  -2235.5 kJ 
B)  -1448.5 kJ 
C)  -178.3 kJ 
D)  178.3 kJ 
E)  2235.5 kJ 
A)  -2235.5 kJ 
B)  -1448.5 kJ 
C)  -178.3 kJ 
D)  178.3 kJ 
E)  2235.5 kJ

Exam 6: Thermochemistry: Energy Flow and Chemical Change

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

Which of the following is not a state function?

The combustion of glucose (C6H12O6) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g) Calculate H°rxn for this reaction. H°f [NH3(g)] = -45.9 kJ/mol; H°f [NO(g)] = 90.3 kJ/mol; H°f [H2O(g)] = -241.8 kJ/mol

Use Hess's Law to calculate the enthalpy change for the reaction WO3(s) + 3H2(g)  W(s) + 3H2O(g) From the following data: 2W(s) + 3O2(g)  2WO3(s) H = -1685.4 kJ 2H2(g) + O2(g)  2H2O(g) H = -477.84 kJ

The standard state of a substance in aqueous solution is a 1 M solution.

Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories?

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g·K)

Your favorite candy bar, Gummy Beakers, contains 1.2 × 106 J of energy while your favorite soft drink, Bolt, contains 6.7 × 105 J. If you eat two packs of Gummy Beakers a day and drink 3 cans of Bolt, what percent of your 2000 Calorie daily food intake is left for broccoli, beans, beef, etc.?

a. State Hess's Law. b. Use the H° data given below to calculate H° for the reaction:

The standard heat (enthalpy) of formation of graphite is zero.

Which one of the following equations represents the formation reaction of CH3OH(l)?

a. Write a balanced equation for the combustion of benzene, C6H6(l) in oxygen. b. The standard heat of combustion of benzene is -3271 kJ/mol. Calculate its standard heat of formation, H°f , given the data: H°f [CO2(g)] = -394 kJ; H°f [H2O(l)] = -286 kJ

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam). Its specific heat capacity is 1.74 J/(g·K). If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C?

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

Calculate the H°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. H°f [CaCO3(s)] = -1206.9 kJ/mol; H°f [CaO(s)] = -635.1 kJ/mol; H°f [CO2(g)] = -393.5 kJ/mol CaCO3(s)  CaO(s) + CO2(g)

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

The Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main Group Elements: Bonding, Structure, and Reactivity

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

The combustion of glucose (C₆H₁₂O₆) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH₃(g) + 5O₂(g)  4NO(g) + 6H₂O(g) Calculate H°_rxn for this reaction. H°_f [NH₃(g)] = -45.9 kJ/mol; H°_f [NO(g)] = 90.3 kJ/mol; H°_f [H₂O(g)] = -241.8 kJ/mol

Use Hess's Law to calculate the enthalpy change for the reaction WO₃(s) + 3H₂(g)  W(s) + 3H₂O(g) From the following data: 2W(s) + 3O₂(g)  2WO₃(s) H = -1685.4 kJ 2H₂(g) + O₂(g)  2H₂O(g) H = -477.84 kJ

Your favorite candy bar, Gummy Beakers, contains 1.2 × 10⁶ J of energy while your favorite soft drink, Bolt, contains 6.7 × 10⁵ J. If you eat two packs of Gummy Beakers a day and drink 3 cans of Bolt, what percent of your 2000 Calorie daily food intake is left for broccoli, beans, beef, etc.?

Which one of the following equations represents the formation reaction of CH₃OH(l)?

a. Write a balanced equation for the combustion of benzene, C₆H₆(l) in oxygen. b. The standard heat of combustion of benzene is -3271 kJ/mol. Calculate its standard heat of formation, H°_f , given the data: H°_f [CO₂(g)] = -394 kJ; H°_f [H₂O(l)] = -286 kJ

Calculate the H°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. H°_f [CaCO₃(s)] = -1206.9 kJ/mol; H°_f [CaO(s)] = -635.1 kJ/mol; H°_f [CO₂(g)] = -393.5 kJ/mol CaCO₃(s)  CaO(s) + CO₂(g)