Deck 6: Energy Relationships in Chemical Reactions

Question 1

Heat is

A)a measure of temperature.
B)a measure of the change in temperature.
C)a measure of thermal energy.
D)a measure of thermal energy transferred between two bodies at different temperature.

Answer 1

a measure of thermal energy transferred between two bodies at different temperature.

Question 2

When 0.7521 g of benzoic acid was burned in a calorimeter containing 1,000. g of water, a temperature rise of 3.60°C was observed. What is the heat capacity of the bomb calorimeter, excluding the water? The heat of combustion of benzoic acid is -26.42 kJ/g.

A)15.87 kJ/°C
B)4.18 kJ/°C
C)5.52 kJ/°C
D)1.34 kJ/°C
E)752.1 kJ/°C

Answer 2

1.34 kJ/°C

Question 3

If 325 g of water at 4.2°C absorbs 12.28 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/g·°C.

A)4.21°C
B)4.8°C
C)9.0°C
D)13.2°C
E)2,938°C

Answer 3

13.2°C

Question 4

Thermal energy is

A)the energy stored within the structural units of chemical substances.
B)the energy associated with the random motion of atoms and molecules.
C)solar energy, i.e. energy that comes from the sun.
D)energy available by virtue of an object's position.

Question 5

Potential energy is

A)the energy stored within the structural units of chemical substances.
B)the energy associated with the random motion of atoms and molecules.
C)solar energy, i.e. energy that comes from the sun.
D)energy available by virtue of an object's position.

Question 6

Radiant energy is

A)the energy stored within the structural units of chemical substances.
B)the energy associated with the random motion of atoms and molecules.
C)solar energy, i.e. energy that comes from the sun.
D)energy available by virtue of an object's position.

Question 7

A beaker contains 115 g of ethanol at 18.2°C. If the ethanol absorbs 1125 J of heat without losing heat to the surroundings, what will be the final temperature of the ethanol? The specific heat of ethanol is 2.46 J/g.°C.

A)4.08°C
B)14.1°C
C)18.4°C
D)22.2°C
E)36.4°C

Question 8

How many degrees of temperature rise will occur when a 25.0 g block of aluminum absorbs 10.0 kJ of heat? The specific heat of Al is 0.900 J/g·°C.

A)0.44°C
B)22.5°C
C)225°C
D)360°C
E)444°C

Question 9

Chemical energy is

A)the energy stored within the structural units of chemical substances.
B)the energy associated with the random motion of atoms and molecules.
C)solar energy, i.e. energy that comes from the sun.
D)energy available by virtue of an object's position.

Question 10

Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C)at 100°C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g·°C)at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks

A)will be higher than 50°C.
B)will be lower than 50°C.
C)will be exactly 50°C.
D)is unrelated to the composition of the blocks.
E)cannot be predicted.

Question 11

How much heat is required to raise the temperature of 2,500 g of water from 27°C to 72°C? The specific heat of water is 4.184 J/g·°C.

A)0.19 kJ
B)10. kJ
C)280 kJ
D)470 kJ
E)750 kJ

Question 12

The specific heat of gold is 0.129 J/g·°C. What is the molar heat capacity of gold?

A)0.039 J/mol·°C
B)0.129 J/mol·°C
C)25.4 J/mol·°C
D)39.0 kJ/mol·°C
E)197 J/mol·°C

Question 13

An endothermic reaction causes the surroundings to

A)warm up.
B)become acidic.
C)condense.
D)decrease in temperature.
E)release CO₂ .

Question 14

Copper metal has a specific heat of 0.385 J/g·°C. Calculate the amount of heat required to raise the temperature of 22.8 g of Cu from 20.0°C to 875°C.

A)1.97 * 10^-5 J
B)1.0* 10^-2 J
C)329 J
D)7.51 kJ
E)10.5 kJ

Question 15

Calculate the amount of heat necessary to raise the temperature of 12.0 g of water from 15.4°C to 93.0°C. The specific heat of water = 4.18 J/g·°C.

A)0.027 J
B)324 J
C)389 J
D)931 J
E)3,890 J

Question 16

Naphthalene combustion can be used to calibrate the heat capacity of a bomb calorimeter. The heat of combustion of naphthalene is -40.1 kJ/g. When 0.8210 g of naphthalene was burned in a calorimeter containing 1,000. g of water, a temperature rise of 4.21°C was observed. What is the heat capacity of the bomb calorimeter excluding the water?

A)32.9 kJ/°C
B)7.8 kJ/°C
C)3.64 kJ/°C
D)1.76 kJ/°C
E)15.3 kJ/°C

Question 17

Which of the following processes is endothermic?

A)O₂(g)+ 2H₂(g) $\rarr$ 2H₂O(g)
B)H₂O(g) $\rarr$ H₂O(l)
C)3O₂(g)+ 2CH₃OH(g) $\rarr$ 2CO₂(g)+ 2H₂O(g)
D)H₂O(s) $\rarr$ H₂O(l)

Question 18

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?

A)0.385 J/g·°C
B)1.83 * 10⁴ J/g·°C
C)2.60 J/g·°C
D)1.32 J/g·°C
E)24.5 J/g·°C

Question 19

An exothermic reaction causes the surroundings to

A)warm up.
B)become acidic.
C)expand.
D)decrease its temperature.
E)release CO₂.

Question 20

A glass containing 200. g of H₂O at 20°C was placed in a refrigerator. The water loses 11.7 kJ as it cools to a constant temperature. What is its new temperature? The specific heat of water is 4.184 J/g·°C.

A)0.013°C
B)4°C
C)6°C
D)14°C
E)34°C

Question 21

Calculate the standard enthalpy change for the reaction 2C₈H₁₈(l)+ 17O₂(g) $\rarr$ 16CO(g)+ 18H₂O(l).
Given:
2C₈H₁₈(l)+ 25O₂(g) $\rarr$ 16CO₂(g)+ 18H₂O(l) $\Delta$ H° = -11,020 kJ/mol
2CO(g)+ O₂(g) $\rarr$ 2CO₂(g) $\Delta$ H° = -566.0 kJ/mol

A)10,450 kJ/mol
B)6,492 kJ/mol
C)15,550 kJ/mol
D)-6,492 kJ/mol
E)-10.450 kJ/mol

Question 22

Given H₂(g)+ (1/2)O₂(g) $\rarr$ H₂O(l), $\Delta$ H° = -286 kJ/mol, determine the standard enthalpy change for the reaction 2H₂O(l) $\rarr$ 2H₂(g)+ O₂(g).

A)( $\Delta$ H°) = -286 kJ/mol
B)( $\Delta$ H°) = +286 kJ/mol
C)( $\Delta$ H°) = -572 kJ/mol
D)( $\Delta$ H°) = +572 kJ/mol
E)( $\Delta$ H°) = -143 kJ/mol

Question 23

Calculate the standard enthalpy of formation of liquid methanol, CH₃OH(l), using the following information: C(graph)+ O₂ $\rarr$ CO₂(g) $\Delta$ H° = -393.5 kJ/mol
H₂(g)+ (1/2)O₂ $\rarr$ H₂O(l) $\Delta$ H° = -285.8 kJ/mol
CH₃OH(l)+ (3/2)O₂(g) $\rarr$ CO₂(g)+ 2H₂O(l) $\Delta$ H° = -726.4 kJ/mol

A)-1,691.5 kJ/mol
B)-238.7 kJ/mol
C)1691.5 kJ/mol
D)47.1 kJ/mol
E)-47.1 kJ/mol

Question 24

For the reaction C(graphite)+ O₂(g) $\rarr$ CO₂(g) $\Delta$ H° = -393 kJ/mol
How many grams of C(graphite)must be burned to release 275 kJ of heat?

A)22.3 g
B)0.70 g
C)12.0 g
D)17.1 g
E)8.40 g

Question 25

A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/°C. If the temperature rise of the calorimeter with water was 0.570°C, calculate the enthalpy of combustion of magnesium. Mg(s)+ 1/2O₂(g) $\rarr$ MgO(s)

A)-3280 kJ/mol
B)-24.8 kJ/mol
C)435 kJ/mol
D)106 kJ/mol
E)-602 kJ/mol

Question 26

Styrene, C₈H₈, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25°C, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C. (Given: $\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol, $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol, $\Delta$ H°_f[H₂O(g)] = -241.8 kJ/mol)

A)323.8 kJ/mol
B)-4249 kJ/mol
C)-8730 kJ/mol
D)-636.7 kJ/mol
E)147.8 kJ/mol

Question 27

Glycine, C₂H₅O₂N, is important for biological energy. The combustion reaction of glycine is given by the equation
4C₂H₅O₂N(s)+ 9O₂(g) $\rarr$ 8CO₂(g)+ 10H₂O(l)+ 2N₂(g) $\Delta$ H°_rxn = -3857 kJ/mol
Given that $\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol, calculate the enthalpy of formation of glycine.

A)-537.2 kJ/mol
B)-268.2 kJ/mol
C)2,149 kJ/mol
D)-3,178 kJ/mol
E)-964 kJ/mol

Question 28

When 0.560 g of Na(s)reacts with excess F₂(g)to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation ( $\Delta$ H°_f)of NaF(s)?

A)24.8 kJ/mol
B)570 kJ/mol
C)-24.8 kJ/mol
D)-7.8 kJ/mol
E)-570 kJ/mol

Question 29

To which one of the following reactions occurring at 25°C does the symbol $\Delta$ H°_f[HNO₃(l)] refer?

A)H(g)+ N(g)+ O₃(g) $\rarr$ HNO₃(l)
B)(1/2)H₂(g)+ (1/2)N₂(g)+ (3/2)O₂(g) $\rarr$ HNO₃(l)
C)HNO₃(l) $\rarr$ (1/2)H₂(g)+ (1/2)N₂(g)+ (3/2)O₂(g)
D)HNO₃(l) $\rarr$ H(g)+ N(g)+ 3O(g)
E)H₂(g)+ N₂(g)+ O₃(g) $\rarr$ HNO₃(l)

Question 30

When 18.5 g of HgO(s)is decomposed to form Hg(l)and O₂(g), 7.75 kJ of heat is absorbed at standard-state conditions. What is the standard enthalpy of formation ( $\Delta$ H°_f)of HgO(s)?

A)-90.7 kJ/mol
B)-7.75 kJ/mol
C)0.419 kJ/mol
D)27.9 kJ/mol
E)143 kJ/mol

Question 31

Find the standard enthalpy of formation of ethylene, C₂H₄(g), given the following data: heat of combustion of C₂H₄(g) = -1411 kJ/mol; $\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol; $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol.

A)52 kJ/mol
B)87 kJ/mol
C)731 kJ/mol
D)1.41 * 10³ kJ/mol
E)2.77 * 10³ kJ/mol

Question 32

During volcanic eruptions, hydrogen sulfide gas is given off and oxidized by air according to the following chemical equation: 2H₂S(g)+ 3O₂(g) $\rarr$ 2SO₂(g)+ 2H₂O(g)
Calculate the standard enthalpy change for the above reaction given:
3S(s)+ 2H₂O(g) $\rarr$ 2H₂S(g)+ SO₂(g) $\Delta$ H° = 146.9 kJ/mol
S(s)+ O₂(g) $\rarr$ SO₂(g) $\Delta$ H° = -296.4 kJ/mol

A)-1036.1 kJ/mol
B)-742.3 kJ/mol
C)-149.5 kJ/mol
D)443.3 kJ/mol
E)742.3 kJ/mol

Question 33

Pentaborane B₅H₉(s)burns vigorously in O₂ to give B₂O₃(s)and H₂O(l). Calculate $\Delta$ H°_rxn for the combustion of 1 mol of B₅H₉. $\Delta$ 0H°_f[B₂O₃(s)] = -1,273.5 kJ/mol
$\Delta$ H°_f[B₅H₉(s)] = 73.2 kJ/mol
$\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol

A)-1,2735 kJ/mol
B)-4,543 kJ/mol
C)-18,170 kJ/mol
D)-9,086 kJ/mol
E)-8,448 kJ/mol

Question 34

Given 2Al(s)+ (3/2)O₂(g) $\rarr$ Al₂O₃(s), $\Delta$ H°_f = -1,670 kJ/mol for Al₂O₃ (s). Determine $\Delta$ H° for the reaction 2Al₂O₃(s) $\rarr$ 4Al(s)+ 3O₂(g).

A)3,340 kJ/mol
B)1,670 kJ/mol
C)-3,340 kJ/mol
D)-1,670 kJ/mol
E)-835 kJ/mol

Question 35

Octane (C₈H₁₈)undergoes combustion according to the following thermochemical equation: 2C₈H₁₈(l)+ 25O₂(g) $\rarr$ 16CO₂(g)+ 18H₂O(l) $\Delta$ H°_rxn = -11,020 kJ/mol.
Given that $\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol, calculate the standard enthalpy of formation of octane.

A)-210 kJ/mol
B)-11,230 kJ/mol
C)22,040 kJ/mol
D)-420 kJ/mol
E)420 kJ/mol

Question 36

Ethanol undergoes combustion in oxygen to produce carbon dioxide gas and liquid water. The standard heat of combustion of ethanol, C₂H₅OH(l), is -1366.8 kJ/mol. Given that $\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol, what is the standard enthalpy of formation of ethanol?

A)3,010 kJ/mol
B)-687.6 kJ/mol
C)-277.6 kJ/mol
D)687.6 kJ/mol
E)1,367 kJ/mol

Question 37

Given the thermochemical equation 2SO₂ + O₂ $\rarr$ 2SO₃, $\Delta$ H°_rxn = -198 kJ/mol, what is the standard enthalpy change for the decomposition of one mole of SO₃?

A)198 kJ/mol
B)-99 kJ/mol
C)99 kJ/mol
D)396 kJ/mol
E)-198 kJ/mol

Question 38

Calculate the standard enthalpy change for the reaction 2C₈H₁₈(l)+ 21O₂(g) $\rarr$ 8CO(g)+ 8CO₂(g)+ 18H₂O(l).
Given:
2C₈H₁₈(l)+ 25O₂(g) $\rarr$ 16CO₂(g)+ 18H₂O(l) $\Delta$ H° = -11,020 kJ/mol
2CO(g)+ O₂(g) $\rarr$ 2CO₂(g) $\Delta$ H° = -566.0 kJ/mol

A)1.0454 * 10⁴ kJ/mol
B)-8,756 kJ/mol
C)1.1586 * 10⁴ kJ/mol
D)-6,492 kJ/mol
E)-1.0454 * 10⁴ kJ/mol

Question 39

A 100. mL sample of 0.200 M aqueous hydrochloric acid is added to 100. mL of 0.200 M aqueous ammonia in a calorimeter whose heat capacity (excluding any water)is 480. J/K. The following reaction occurs when the two solutions are mixed. HCl(aq)+ NH₃(aq) $\rarr$ NH₄Cl(aq)
The temperature increase is 2.34°C. Calculate $\Delta$ H per mole of HCl and NH₃ reacted.

A)154 kJ/mol
B)1.96 kJ/mol
C)485 kJ/mol
D)-1.96 kJ/mol
E)-154 kJ/mol

Question 40

To which one of the following reactions occurring at 25°C does the symbol $\Delta$ H°_f[H₂SO₄(l)] refer?

A)2H(g)+ S(g)+ 4O(g) $\rarr$ H₂SO₄(l)
B)H₂(g)+ S(g)+ 2O₂(g) $\rarr$ H₂SO₄(l)
C)H₂SO₄(l) $\rarr$ H₂(g)+ S(s)+ 2O₂(g)
D)H₂SO₄(l) $\rarr$ 2H(g)+ S(s)+ 4O(g)
E)H₂(g)+ S(s)+ 2O₂(g) $\rarr$ H₂SO₄(l)

Question 41

Given that CaO(s)+ H₂O(l) $\rarr$ Ca(OH)₂(s), $\Delta$ H°_rxn = -64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat?

A)6.92 g
B)56.1 g
C)455 g
D)606 g
E)3.40 * 10⁴ g

Question 42

Find the heat absorbed from the surroundings when 15 g of O₂ reacts according to the equation O + O₂ $\rarr$ O₃, $\Delta$ H°_rxn= -103 kJ/mol.

A)4.6 * 10^-3 kJ
B)48 kJ
C)96 kJ
D)32 kJ
E)110 kJ

Question 43

At 25°C, the standard enthalpy of formation of KCl(s)is -435.87 kJ/mol. When one mole of KCl(s)is formed by reacting potassium vapor and chlorine gas at 25°C, the standard enthalpy of reaction is -525.86 kJ/mol. Find $\Delta$ H° for the sublimation of potassium, K(s) $\rarr$ K(g), at 25°C.

A)-345.88 kJ/mol
B)45.00 kJ/mol
C)345.88 kJ/mol
D)89.99 kJ/mol
E)-525.86 kJ/mol

Question 44

The combustion of octane produces heat according to the equation 2C₈H₁₈(l)+ 25O₂(g) $\rarr$ 16CO₂(g)+ 18H₂O(l) $\Delta$ H°_rxn= -11,020 kJ/mol
What is the heat of combustion per gram of octane?

A)-5,510 kJ/g
B)-96.5 kJ/g
C)-48.2 kJ/g
D)-193 kJ/g
E)-6.292 * 10⁵ kJ/g

Question 45

Determine the heat given off to the surroundings when 9.0 g of aluminum reacts according to the equation 2Al + Fe₂O₃ $\rarr$ Al₂O₃ + 2Fe, $\Delta$ H°_rxn= -849 kJ/mol.

A)7.6 * 10³ kJ
B)2.8 * 10² kJ
C)1.4 * 10² kJ
D)5.6 * 10² kJ
E)2.5 * 10³ kJ

Question 46

The combustion of pentane produces heat according to the equation C₅H₁₂(l)+ 8O₂(g) $\rarr$ 5CO₂(g)+ 6H₂O(l) $\Delta$ H°_rxn= -3,510 kJ/mol
How many grams of CO₂ are produced per 2.50 * 10³ kJ of heat released?

A)0.0809 g
B)3.56 g
C)31.3 g
D)157 g
E)309 g

Question 47

At 25°C, the standard enthalpy of formation of anhydrous sodium carbonate is -1130.9 kJ/mol, whereas the standard enthalpy of formation of sodium carbonate monohydrate is -1430.1 kJ/mol. Determine $\Delta$ H° at 25°C for the reaction Na₂CO₃(s)+ H₂O(l) $\rarr$ Na₂CO₃·H₂O(s).
(Given: $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol)

A)-13.4 kJ/mol
B)-285.8 kJ/mol
C)-585.0 kJ/mol
D)-299.2 kJ/mol
E)-156.3 kJ/mol

Question 48

An average home in Colorado requires 20. GJ of heat per month. How many grams of natural gas (methane)must be burned to supply this energy? CH₄(g)+ 2O₂(g) $\rarr$ CO₂(g)+ 2H₂O(l) $\Delta$ H°_rxn= -890.4 kJ/mol

A)1.4 * 10³ g
B)3.6 * 10⁵ g
C)7.1 * 10^-4 g
D)2.2 * 10⁴ g
E)1.4 * 10⁴ g

Question 49

Methanol (CH₃OH)burns according to the equation 2CH₃OH(l)+ 3O₂(g) $\rarr$ 2CO₂(g)+ 4H₂O(l), $\Delta$ H°_rxn = -1454 kJ/mol.
How much heat, in kilojoules, is given off when 75.0 g of methanol is burned?

A)727 kJ
B)3.22 * 10³ kJ
C)1.45 * 10³ kJ
D)1.70 * 10^-3 kJ
E)3.41 * 10³ kJ

Question 50

The enthalpy change when a strong acid is neutralized by strong base is -56.1 kJ/mol. If 12.0 mL of 6.00 M HBr at 21.30°C is mixed with 300. mL of 0.250 M NaOH, also at 21.30°C, what will be the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/g·°C, and that the density of the final solution is that of water.)

A)18.20°C
B)24.53°C
C)101.8°C
D)24.40°C
E)34.25°C

Question 51

Calcium oxide and water react in an exothermic reaction: CaO(s)+ H₂O(l) $\rarr$ Ca(OH)₂(s) $\Delta$ H°_rxn = -64.8 kJ/mol
How much heat would be liberated when 7.15 g CaO(s)is dropped into a beaker containing 152g H₂O?

A)1.97 * 10^-3 kJ
B)8.26 kJ
C)508 kJ
D)547 kJ
E)555 kJ

Question 52

According to the first law of thermodynamics:

A)Energy is neither lost nor gained in any energy transformations.
B)Perpetual motion is possible.
C)Energy is conserved in quality but not in quantity.
D)Energy is being created as time passes. We have more energy in the universe now than when time began.

Question 53

The combustion of butane produces heat according to the equation 2C₄H₁₀(g)+ 13O₂(g) $\rarr$ 8CO₂(g)+ 10H₂O(l) $\Delta$ H°_rxn = -5,314 kJ/mol
What is the heat of combustion per gram of butane?

A)-32.5 kJ/g
B)-45.7 kJ/g
C)-91.5 kJ/g
D)-2,656 kJ/g
E)-15,440 kJ/g

Question 54

Calculate the amount of work done, in joules, when 2.5 mole of H₂O vaporizes at 1.0 atm and 25°C. Assume the volume of liquid H₂O is negligible compared to that of vapor. (1 L·atm = 101.3 J)

A)6,190 kJ
B)6.19 kJ
C)61.1 J
D)5.66 kJ
E)518 J

Question 55

The enthalpy change when a strong acid is neutralized by strong base is -56.1 kJ/mol. If 135 mL of 0.450 M HI at 23.15°C is mixed with 145 mL of 0.500 M NaOH, also at 23.15°C, what will be the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/g·°C, and that the density of the final solution is that of water.)

A)26.06°C
B)29.19°C
C)32.35°C
D)20.24°C
E)36.57°C

Question 56

Solid sodium peroxide (Na₂O₂)reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released when 250.0 L of oxygen gas is produced from the reaction of sodium peroxide and water if the reaction is carried out in an open container at 1.000 atm pressure and 25°C? (Given: $\Delta$ H°_f[Na₂O₂(s)] = -510.9 kJ/mol; $\Delta$ H°_f[NaOH(aq)] = -469.2 kJ/mol; $\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol)

A)35,400 kJ
B)1740 kJ
C)141.7 kJ
D)3330 kJ
E)2900 kJ

Question 57

The combustion of butane produces heat according to the equation 2C₄H₁₀(g)+ 13O₂(g) $\rarr$ 0 8CO₂(g)+ 10H₂O(l) $\Delta$ H°_rxn= -5,314 kJ/mol
How many grams of butane must be burned to release 1.00 * 10⁴ kJ of heat?

A)30.9 g
B)61.8 g
C)109 g
D)153 g
E)219 g

Question 58

The combustion of butane produces heat according to the equation 2C₄H₁₀(g)+ 13O₂(g) $\rarr$ 8CO₂(g)+ 10H₂O(l) $\Delta$ H°_rxn= -5,314 kJ/mol
How many grams of CO₂ are produced per 1.00 * 10⁴ kJ of heat released?

A)23.4 g
B)44.0 g
C)82.3 g
D)187 g
E)662 g

Question 59

Ethanol (C₂H₅OH)burns according to the equation C₂H₅OH(l)+ 3O₂(g) $\rarr$ 2CO₂(g)+ 3H₂O(l), $\Delta$ H°_rxn = -1367 kJ/mol.
How much heat is released when 35.0 g of ethanol is burned?

A)1,797 kJ
B)1,367 kJ
C)9.61 * 10^-4 kJ
D)4.78 * 10⁴ kJ
E)1,040 kJ

Question 60

Given the thermochemical equation 2SO₂(g)+ O₂(g) $\rarr$ 2SO₃(g), $\Delta$ H°_rxn= -198 kJ/mol, how much heat is evolved when 600. g of SO₂ is burned?

A)5.46 * 10^-2 kJ
B)928 kJ
C)1.85 * 10³ kJ
D)59,400 kJ
E)3.71 * 10³ kJ

Question 61

Aluminum oxide can be reduced to aluminum metal using carbon, the other reaction product being carbon monoxide. Determine the enthalpy change when 12.5 g of aluminum is produced by this method. [ $\Delta$ H°_f(carbon monoxide)= -110.5 kJ/mol; $\Delta$ H°_f(aluminum oxide)= -1669.8 kJ/mol]

A)725 kJ
B)697 kJ
C)310 kJ
D)361 kJ
E)1504 kJ

Question 62

For which of these reactions will the difference between $\Delta$ H° and $\Delta$ E° be the greatest?

A)2H₂O₂(l) $\rarr$ 2H₂O(l)+ O₂(g)
B)CaCO₃(s) $\rarr$ CaO(s)+ CO₂(g)
C)NO(g)+ O₃(g) $\rarr$ NO₂(g)+ O₂(g)
D)2C₂H₆(g)+ 7O₂(g) $\rarr$ 4CO₂(g)+ 6H₂O(l)
E)4NH₃(g)+ 5O₂(g) $\rarr$ 4NO(g)+ 6H₂O(g)

Question 63

Which of the following processes always results in an increase in the energy of a system?

A)The system loses heat and does work on the surroundings.
B)The system gains heat and does work on the surroundings.
C)The system loses heat and has work done on it by the surroundings.
D)The system gains heat and has work done on it by the surroundings.
E)None of these is always true.

Question 64

Ozone (O₃)in the atmosphere can be converted to oxygen gas by reaction with nitric oxide (NO). Nitrogen dioxide is also produced in the reaction. What is the enthalpy change when 8.50L of ozone at a pressure of 1.00 atm and 25°C reacts with 12.00 L of nitric oxide at the same initial pressure and temperature? [ $\Delta$ H°_f(NO)= 90.4 kJ/mol; $\Delta$ H°_f(NO₂)= 33.85 kJ/mol; $\Delta$ H°_f(O₃)= 142.2 kJ/mol]

A)-69.2 kJ
B)-19.7 kJ
C)-1690 kJ
D)-97.6 kJ
E)-167 kJ

Question 65

The heat of solution of ammonium chloride is 15.2 kJ/mol. If a 6.134 g sample of NH₄Cl is added to 65.0 mL of water in a calorimeter at 24.5°C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 365. J/°C.)

A)27.1°C
B)18.6°C
C)19.7°C
D)21.9°C
E)30.4°C

Question 66

A 26.2 g piece of copper metal is heated from 21.5°C to 201.6°C. Calculate the amount of heat absorbed by the metal. The specific heat of Cu is 0.385 J/g·°C.

Question 67

A gas is allowed to expand, at constant temperature, from a volume of 1.0 L to 10.1 L against an external pressure of 0.50 atm. If the gas absorbs 250 J of heat from the surroundings, what are the values of q, w, and $\Delta$ E?

A)
B)
C)
D)
E)

Question 68

Given the following $\Delta$ H° values,
H₂(g)+ O₂(g) $\rarr$ H₂O(l) $\Delta$ H°_f = -285.8 kJ/mol
H₂O₂(l) $\rarr$ H₂(g)+ O₂(g) $\Delta$ H°_rxn = 187.6 kJ/mol
calculate $\Delta$ H°_rxn for the reaction H₂O₂(l) $\rarr$ H₂O(l)+ O₂(g),

Question 69

The heat of solution of ammonium nitrate is 26.2 kJ/mol. If a 5.368 g sample of NH₄NO₃ is added to 40.0 mL of water in a calorimeter at 23.5°C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 650. J/°C.)

A)14.3°C
B)20.8°C
C)-7.7°C
D)25.6°C
E)21.4°C

Question 70

The enthalpy of combustion of acetylene C₂H₂ is described by
C₂H₂(g)+ (5/2)O₂(g) $\rarr$ 2CO₂(g)+ H₂O(l) $\Delta$ H°_rxn= -1299 kJ/mol
Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation
$\Delta$ H°_f[CO₂(g)] = -393.5 kJ/mol
$\Delta$ H°_f[H₂O(l)] = -285.8 kJ/mol

Question 71

A 0.1946 g piece of magnesium metal is burned in a constant-volume calorimeter that has a heat capacity of 1349 J/°C. The calorimeter contains 500. g of water and the temperature rise is 1.40°C. Calculate the heat of combustion of magnesium metal in kJ/g, given that the specific heat of water = 4.184 J/g·°C.

Question 72

For which of these reactions will the difference between $\Delta$ H° and $\Delta$ E° be the smallest?

A)N₂(g)+ 3H₂(g) $\rarr$ 2NH₃(g)
B)4PH₃(g) $\rarr$ P₄(g)+ 6H₂(g)
C)H₂(g)+ Cl₂(g) $\rarr$ 2HCl(g)
D)CO₂(g)+ 2H₂O(l) $\rarr$ CH₄(g)+ 2O₂(g)
E)P₄(s)+ 10Cl₂(g) $\rarr$ 4PCl₅(s)

Question 73

The bond enthalpy of the Br-Cl bond is equal to $\Delta$ H° for the reaction BrCl(g) $\rarr$ Br(g)+ Cl(g).
Use the following data to find the bond enthalpy of the Br-Cl bond.

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 74

At 25°C, the following heats of reaction are known: At the same temperature, use Hess's law to calculate $\Delta$ H°_rxn for the reaction: ClF(g)+ F₂(g) $\rarr$ ClF₃(g)

A)-217.5 kJ/mol
B)-130.2 kJ/mol
C)217.5 kJ/mol
D)-108.7 kJ/mol
E)465.4 kJ/mol

Question 75

Define specific heat.

Question 76

A 0.3423 g sample of pentane, C₅H₁₂, was burned in a bomb calorimeter. The temperature of the calorimeter and the 1.000 kg of water contained therein rose from 20.22°C to 22.82°C. The heat capacity of the calorimeter is 2.21 kJ/°C. The heat capacity of water = 4.184 J/g·°C. How much heat was given off during combustion of the sample of pentane?

Question 77

A gas is compressed in a cylinder from a volume of 20.0 L to 2.0 L by a constant pressure of 10.0 atm. Calculate the amount of work done on the system.

A)1.01 * 10⁴ J
B)-180 J
C)1.81 * 10⁴ J
D)-1.81 * 10⁴ J
E)180 J

Question 78

Calculate the enthalpy of reaction for H₂(g)+ C₂H₄(g) $\rarr$ C₂H₆(g).
[ $\Delta$ H°_f(C₂H₄(g))= 52.3 kJ/mol; $\Delta$ H°_f(C₂H₆(g))= -84.7 kJ/mol]

Question 79

How many grams of ethylene (C₂H₄)would have to be burned to produce 450 kJ of heat?
C₂H₄(g)+ 3O₂(g) $\rarr$ 2CO₂(g)+ H₂O(l) $\Delta$ H°_rxn= -1411 kJ/mol

Question 80

Calculate the amount of work done against an atmospheric pressure of 1.00 atm when 500.0 g of zinc dissolves in excess acid at 30.0°C. Zn(s)+ 2H⁺(aq) $\rarr$ Zn²⁺(aq)+ H₂(g)

A)w = +22.4 kJ
B)w = +24.9 kJ
C)w = 0
D)w = -2.52 kJ
E)w = -19.3 kJ