Question 1

Identify what a bomb calorimeter measures.

Accepted Answer

A)  measures ΔH for aqueous solutions 
B)  measures ΔU for combustion reactions 
C)  measures ΔH for oxidation solutions 
D)  measures ΔT for hydrolysis solutions 
E)  measures ΔU for reduction reactions 
A)  measures ΔH for aqueous solutions 
B)  measures ΔU for combustion reactions 
C)  measures ΔH for oxidation solutions 
D)  measures ΔT for hydrolysis solutions 
E)  measures ΔU for reduction reactions

Question 2

A piece of iron (mass = 25.0 g) at 398 K is placed in a styrofoam coffee cup containing 25.0 mL of water at 298 K. Assuming that no heat is lost to the cup or the surroundings, what will the final temperature of the water be? The specific heat capacity of iron = 0.449 J   °C-1 and water = 4.184 J   °C-1.

Accepted Answer

A)  348 K 
B)  308 K 
C)  287 K 
D)  325 K 
E)  388 K 
A)  348 K 
B)  308 K 
C)  287 K 
D)  325 K 
E)  388 K

Question 3

When 50.0 mL of 0.400 mol L-1 Ca(NO3)2 is added to 50.0 mL of 0.800 mol L-1 NaF, CaF2 precipitates, as shown in the net ionic equation below. The initial temperature of both solutions is 24.0 °C. Assuming that the reaction goes to completion, and that the resulting solution has a mass of 100.00 g and a specific heat of 4.18 J     , calculate the final temperature of the solution. Ca2+(aq) + 2F-(aq) → CaF2(s)   H = -11.5 kJ

Accepted Answer

A)  23.45 °C 
B)  24.55 °C 
C)  25.10 °C 
D)  25.65 °C 
A)  23.45 °C 
B)  24.55 °C 
C)  25.10 °C 
D)  25.65 °C

Question 4

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   . Fe3O4(s) → 3Fe(s) + 2O2(g)   H° = +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

Question 5

According to the following reaction, how much energy is evolved during the reaction of 2.50 L B2H6 and 5.65 L Cl2 (both gases are initially at STP)? The molar mass of B2H6 is 27.67 g   . B2H6(g) + 6Cl2(g) → 2BCl3(g) + 6HCl(g)   H° = -1396 kJ

Accepted Answer

A)  57.8 kJ 
B)  156 kJ 
C)  215 kJ 
D)  352 kJ 
E)  508 kJ 
A)  57.8 kJ 
B)  156 kJ 
C)  215 kJ 
D)  352 kJ 
E)  508 kJ

Question 6

Identify the greatest source of energy worldwide.

Accepted Answer

A)  petroleum 
B)  natural gas 
C)  wood 
D)  coal 
E)  nuclear power 
A)  petroleum 
B)  natural gas 
C)  wood 
D)  coal 
E)  nuclear power

Question 7

Why are the standard heats of formation for elements in their most stable form assigned a value of 0?

Accepted Answer

We can't measure absolute enthalpy, but

Question 8

At constant pressure, the combustion of 20.0 g of C2H6(g) releases 1036 kJ of heat. What is ΔH for the reaction given below? 
2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)

Accepted Answer

A)  -173 kJ   
B)  -779 kJ   
C)  -1560 kJ   
D)  -3120 kJ   
A)  -173 kJ   
B)  -779 kJ   
C)  -1560 kJ   
D)  -3120 kJ

Question 9

Using the following thermochemical equation, determine the amount of heat produced per kg of CO2 formed during the combustion of benzene (C6H6). 2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(g)   H° = -6278 kJ

Accepted Answer

A)  1.43 × 105 kJ (kg CO2)-1 
B)  2.30 × 104 kJ (kg CO2)-1 
C)  4.34 × 104 kJ (kg CO2)-1 
D)  1.19 × 104 kJ (kg CO2)-1 
E)  8.40 × 105 kJ (kg CO2)-1 
A)  1.43 × 105 kJ (kg CO2)-1 
B)  2.30 × 104 kJ (kg CO2)-1 
C)  4.34 × 104 kJ (kg CO2)-1 
D)  1.19 × 104 kJ (kg CO2)-1 
E)  8.40 × 105 kJ (kg CO2)-1

Question 10

When 2.50 g of Ba(s) is added to 100.00 g of water in a container open to the atmosphere, the reaction shown below occurs and the temperature of the resulting solution rises from 22.00 °C to 40.32 °C. If the specific heat of the solution is 4.18 J     , calculate   for the reaction, as written. Ba(s) + 2H2O(l) → Ba(OH)2(aq) + H2(g)   = ?

Accepted Answer

A)  -431 kJ   
B)  -3.14 kJ   
C)  +3.14 kJ   
D)  +431 kJ   
A)  -431 kJ   
B)  -3.14 kJ   
C)  +3.14 kJ   
D)  +431 kJ

Question 11

Calculate the enthalpy of solution for the dissolution of sodium chloride, NaCl, molar mass = 58.443 g mol-1. When 6.93 g of NaCl is dissolved in a coffee cup calorimeter containing 100.0 mL of water the temperature dropped from 23.5 °C to 22.4 °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.

Accepted Answer

A)  -2.8 kJ mol-1 
B)  3.9 kJ mol-1 
C)  -6.4 kJ mol-1 
D)  4.1 kJ mol-1 
E)  6.3 kJ mol-1 
A)  -2.8 kJ mol-1 
B)  3.9 kJ mol-1 
C)  -6.4 kJ mol-1 
D)  4.1 kJ mol-1 
E)  6.3 kJ mol-1

Question 12

A chemist wishes to calibrate a bomb calorimeter, so she combusts 5.58 g of 4-pentenoic acid, ΔcombustionU = -26.77 kJ g-1, which causes a temperature change from 23.4 °C to 38.9 °C. What should the chemist report for the value of Ccal?

Accepted Answer

A)  6.10 kJ °C-1 
B)  17.5 kJ °C-1 
C)  28.7 kJ °C-1 
D)  9.64 kJ °C-1 
E)  7.61 kJ °C-1 
A)  6.10 kJ °C-1 
B)  17.5 kJ °C-1 
C)  28.7 kJ °C-1 
D)  9.64 kJ °C-1 
E)  7.61 kJ °C-1

Question 13

Where does the energy absorbed during an endothermic reaction go?

Accepted Answer

During an endothermic reaction, the prod

Question 14

Choose the thermochemical equation that illustrates ΔH° for Li2SO4.

Accepted Answer

A)  2Li+(aq) + SO42-(aq) → Li2SO4(aq) 
B)  2Li(s) + 1/8 S8(s, rhombic) + 2O2(g) → Li2SO4(s) 
C)  Li2SO4(aq) → 2Li+(aq) + SO42-(aq) 
D)  8Li2SO4(s) → 16Li(s) + S8(s, rhombic) + 16O2(g) 
E)  16Li(s) + S8(s, rhombic) + 16O2(g) → 8Li2SO4(s) 
A)  2Li+(aq) + SO42-(aq) → Li2SO4(aq) 
B)  2Li(s) + 1/8 S8(s, rhombic) + 2O2(g) → Li2SO4(s) 
C)  Li2SO4(aq) → 2Li+(aq) + SO42-(aq) 
D)  8Li2SO4(s) → 16Li(s) + S8(s, rhombic) + 16O2(g) 
E)  16Li(s) + S8(s, rhombic) + 16O2(g) → 8Li2SO4(s)

Question 15

A 50.0 g sample of liquid water at 25.0 °C is mixed with 19.0 g of water at 87.0 °C. The final temperature of the water is ________°C.

Accepted Answer

A)  93.6 
B)  13.0 
C)  62.0 
D)  36.1 
E)  42.1 
A)  93.6 
B)  13.0 
C)  62.0 
D)  36.1 
E)  42.1

Question 16

At 1.0133 bar, the heat of sublimation of gallium is 277 kJ   and the heat of vaporization is 271 kJ   . To the correct number of significant figures, how much heat is required to melt 5.50 mol of gallium at 1.0133 bar?

Accepted Answer

A)  6 kJ 
B)  33 kJ 
C)  244 kJ 
D)  274 kJ 
A)  6 kJ 
B)  33 kJ 
C)  244 kJ 
D)  274 kJ

Question 17

What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g   by 10.2 °C? (The specific heat of the solution is 3.733 J     .)

Accepted Answer

A)  -7.43 kJ 
B)  -12.51 kJ 
C)  8.20 kJ 
D)  -11.9 kJ 
E)  6.51 kJ 
A)  -7.43 kJ 
B)  -12.51 kJ 
C)  8.20 kJ 
D)  -11.9 kJ 
E)  6.51 kJ

Question 18

Match the following.
-+ΔU

Accepted Answer

A) energy flows out of the system into the surroundings 
B) energy flows into the system from the surroundings 
C) work done by the system on the surroundings 
D) the system loses thermal energy to the surroundings 
E) the system gains thermal energy from the surroundings
F)work done on the system by the surroundings 
A) energy flows out of the system into the surroundings 
B) energy flows into the system from the surroundings 
C) work done by the system on the surroundings 
D) the system loses thermal energy to the surroundings 
E) the system gains thermal energy from the surroundings
F)work done on the system by the surroundings

Question 19

Calculate the heat transfer, in J, when 5.00 g of chromium (specific heat capacity = 0.449 J g-1 °C-1) at 0.00 °C is placed in 50.0 mL of water. The final temperature of the water is 23.8 °C. The chromium is defined as the system in this scenario.

Accepted Answer

A)  -53 J 
B)  53 J 
C)  82 J 
D)  -82 J 
E)  93 J 
A)  -53 J 
B)  53 J 
C)  82 J 
D)  -82 J 
E)  93 J

Question 20

Which of the following signs on q and w represent a system that is doing work on the surroundings as well as losing heat to 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.

Exam 6: Thermochemistry

Identify what a bomb calorimeter measures.

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 . Fe3O4(s) → 3Fe(s) + 2O2(g) H° = +1118 kJ

According to the following reaction, how much energy is evolved during the reaction of 2.50 L B2H6 and 5.65 L Cl2 (both gases are initially at STP)? The molar mass of B2H6 is 27.67 g . B2H6(g) + 6Cl2(g) → 2BCl3(g) + 6HCl(g) H° = -1396 kJ

Identify the greatest source of energy worldwide.

Why are the standard heats of formation for elements in their most stable form assigned a value of 0?

At constant pressure, the combustion of 20.0 g of C2H6(g) releases 1036 kJ of heat. What is ΔH for the reaction given below? 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)

Using the following thermochemical equation, determine the amount of heat produced per kg of CO2 formed during the combustion of benzene (C6H6). 2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(g) H° = -6278 kJ

A chemist wishes to calibrate a bomb calorimeter, so she combusts 5.58 g of 4-pentenoic acid, ΔcombustionU = -26.77 kJ g-1, which causes a temperature change from 23.4 °C to 38.9 °C. What should the chemist report for the value of Ccal?

Where does the energy absorbed during an endothermic reaction go?

Choose the thermochemical equation that illustrates ΔH° for Li2SO4.

A 50.0 g sample of liquid water at 25.0 °C is mixed with 19.0 g of water at 87.0 °C. The final temperature of the water is ________°C.

At 1.0133 bar, the heat of sublimation of gallium is 277 kJ and the heat of vaporization is 271 kJ . To the correct number of significant figures, how much heat is required to melt 5.50 mol of gallium at 1.0133 bar?

What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g by 10.2 °C? (The specific heat of the solution is 3.733 J .)

Match the following. -+ΔU

Calculate the heat transfer, in J, when 5.00 g of chromium (specific heat capacity = 0.449 J g-1 °C-1) at 0.00 °C is placed in 50.0 mL of water. The final temperature of the water is 23.8 °C. The chromium is defined as the system in this scenario.

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

Units of Measurement for Physical and Chemical Change

Atoms and Elements

Molecules, Compounds, and Nomenclature

Chemical Reactions and Stoichiometry

Gases

The Quantum-Mechanical Model of the Atom

Periodic Properties of the Elements

Chemical Bonding I: Lewis Theory

Chemical Bonding Ii: Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory

Liquids, Solids, and Intermolecular Forces

Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Aqueous Ionic Equilibrium

Gibbs Energy and Thermodynamics

Electrochemistry

Radioactivity and Nuclear Chemistry

Organic Chemistry I: Structures

Organic Chemistry Ii: Reactions

Biochemistry

Chemistry of the Nonmetals

Metals and Metallurgy

Transition Metals and Coordination Compounds

Filters

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 . Fe₃O₄(s) → 3Fe(s) + 2O₂(g) H°= +1118 kJ

According to the following reaction, how much energy is evolved during the reaction of 2.50 L B₂H₆ and 5.65 L Cl₂(both gases are initially at STP)? The molar mass of B₂H₆is 27.67 g . B₂H₆(g) + 6Cl₂(g) → 2BCl₃(g) + 6HCl(g) H°= -1396 kJ

At constant pressure, the combustion of 20.0 g of C₂H₆(g) releases 1036 kJ of heat. What is ΔH for the reaction given below? 2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l)

Using the following thermochemical equation, determine the amount of heat produced per kg of CO₂ formed during the combustion of benzene (C₆H₆). 2C₆H₆(l) + 15O₂(g) → 12CO₂(g) + 6H₂O(g) H°= -6278 kJ

A chemist wishes to calibrate a bomb calorimeter, so she combusts 5.58 g of 4-pentenoic acid, Δ_combustionU = -26.77 kJ g^-1, which causes a temperature change from 23.4 °C to 38.9 °C. What should the chemist report for the value of C_cal?

Choose the thermochemical equation that illustrates ΔH° for Li₂SO₄.

Calculate the heat transfer, in J, when 5.00 g of chromium (specific heat capacity = 0.449 J g^-1 °C^-1) at 0.00 °C is placed in 50.0 mL of water. The final temperature of the water is 23.8 °C. The chromium is defined as the system in this scenario.