Deck 6: Thermochemistry

Question 1

Thermal energy is 4

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.

Answer 1

the energy associated with the random motion of atoms and molecules.

Question 2

If 10.6 moles of water at 35 ^$\circ$ C absorbs 12.30 kJ, what is the final temperature of the water The specific heat of water is 4.184 J/g· ^$\circ$ C.

A) 15 ^$\circ$ C
B) 20 ^$\circ$ C
C) 35 ^$\circ$ C
D) 50. ^$\circ$ C
E) 312 ^$\circ$ C

Answer 2

50. ^$\circ$ C

Question 3

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.

Answer 3

solar energy, i.e. energy that comes from the sun.

Question 4

When 0.7521 g of benzoic acid was burned in a calorimeter containing 1,000. g of water, a temperature rise of 3.60 ^$\circ$ 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) 1.34 kJ/ ^$\circ$ C
B) 4.18 kJ/ ^$\circ$ C
C) 5.52 kJ/ ^$\circ$ C
D) 15.87 kJ/ ^$\circ$ C
E) 752.1 kJ/ ^$\circ$ C

Question 5

A 22.0 g block of copper at 45 ^$\circ$ C absorbs 2.50 kJ of heat. Given the specific heat of Cu is 0.385 J/g· ^$\circ$ C what will be the final temperature of the Cu

A) 45 ^$\circ$ C
B) 340. ^$\circ$ C
C) 295 ^$\circ$ C
D) 30. ^$\circ$ C
E) 250. ^$\circ$ C

Question 6

Three separate 3.5g blocks of Al, Cu, and Fe at 25 ^$\circ$ C each absorb 0.505 kJ of heat. Which block reaches the highest temperature The specific heats of Al, Cu, and Fe are 0.900 J/g· ^$\circ$ C, 0.385J/g· ^$\circ$ C, and 0.444 J/g· ^$\circ$ C, respectively.

A) Al
B) Cu
C) Fe
D) Al and Cu
E) Fe and Cu

Question 7

Calculate the amount of heat necessary to raise the temperature of 135.0 g of water from 50.4 ^$\circ$ F to 85.0 ^$\circ$ F. The specific heat of water = 4.184 J/g· ^$\circ$ C.

A) 1.1 kJ
B) 10.9 kJ
C) 16.6 kJ
D) 19.5 kJ
E) 48.0 kJ

Question 8

Aluminum metal has a specific heat of 0.900 J/g· ^$\circ$ C. Calculate the amount of heat required to raise the temperature of 10.5 moles of Al from 30.5 ^$\circ$ C to 225 ^$\circ$ C.

A) 1.84 kJ
B) 2.41 kJ
C) 65.1 kJ
D) 49.6 kJ
E) 57.3 kJ

Question 9

Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g· ^$\circ$ C) at 100 ^$\circ$ C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g· ^$\circ$ C) at 0 ^$\circ$ 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 ^$\circ$ C.
B) will be lower than 50 ^$\circ$ C.
C) will be exactly 50 ^$\circ$ C.
D) is unrelated to the composition of the blocks.
E) cannot be predicted.

Question 10

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 11

The specific heat of gold is 0.129 J/g· ^$\circ$ C. What is the molar heat capacity of gold

A) 0.039 J/mol· ^$\circ$ C
B) 0.129 J/mol· ^$\circ$ C
C) 25.4 J/mol· ^$\circ$ C
D) 39.0 kJ/mol· ^$\circ$ C
E) 197 J/mol· ^$\circ$ C

Question 12

A 135 g sample of H₂O at 85 ^$\circ$ C is cooled. The water loses a total of 15 kJ of energy in the cooling process. What is the final temperature of the water The specific heat of water is 4.184 J/g· ^$\circ$ C.

A) 27 ^$\circ$ C
B) 58 ^$\circ$ C
C) 70 ^$\circ$ C
D) 84 ^$\circ$ C
E) 112 ^$\circ$ C

Question 13

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/ ^$\circ$ C. What is the specific heat of copper

A) 0.385 J/g· ^$\circ$ C
B) 1.32 J/g· ^$\circ$ C
C) 2.60 J/g· ^$\circ$ C
D) 24.5 J/g· ^$\circ$ C
E) 1.83 * 10⁴ J/g· ^$\circ$ C

Question 14

Given the specific heat for aluminum is 0.900 J/g· ^$\circ$ C, how much heat is released when a 3.8 g sample of Al cools from 450.0 ^$\circ$ C to 25 ^$\circ$ C

A) 54 J
B) 60 J
C) 86 J
D) 1.5 kJ
E) 1.7 kJ

Question 15

A beaker contains 115 g of ethanol at 18.2 ^$\circ$ 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* ^$\circ$ C.

A) 4.08 ^$\circ$ C
B) 14.1 ^$\circ$ C
C) 18.4 ^$\circ$ C
D) 22.2 ^$\circ$ C
E) 36.4 ^$\circ$ C

Question 16

An endothermic reaction causes the surroundings to

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

Question 17

An exothermic reaction causes the surroundings to

A) increase in temperature
B) decrease in temperature.
C) become acidic.
D) release CO₂.
E) expand.

Question 18

How much heat is required to raise the temperature of 1.5 x 10³ g of water from 45 ^$\circ$ F to 130. ^$\circ$ F The specific heat of water is 4.184 J/g· ^$\circ$ C.

A) 3.0 x 10¹ kJ
B) 3.0 x 10² kJ
C) 3.4 x 10² kJ
D) 5.3 x 10² kJ
E) 8.2 x 10² kJ

Question 19

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.

Question 20

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 21

Which of the following processes is exothermic

A) CH₄(g) + 2 O₂(g) $\rarr$ CO₂(g) + 2 H₂O(l)
B) CO₂(g) + 2 H₂O(l) $\rarr$ CH₄(g) + 2 O₂(g)
C) CO₂(s) $\rarr$ CO₂(g)
D) H₂O(l) $\rarr$ H₂O(g)
E) 6 H₂O(g) + 4 CO₂(g) $\rarr$ 2 C₂H₆(g) + 7 O₂(g)

Question 22

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 ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol, what is the standard enthalpy of formation of ethanol

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

Question 23

Which of the following processes is endothermic, given the following:
S(s) + O₂(g) $\rarr$ SO₂(g) $\Delta$ H = -299 kJ/mol
S(s) + 3/2 O₂(g) $\rarr$ SO₃(g) $\Delta$ H = -395 kJ/mol

A) 2 S(s) + 2 O₂(g) $\rarr$ 2 SO₂(g)
B) ½ S(s) + ½ O₂(g) $\rarr$ ½ SO₂(g)
C) 2 S(s) + 5/2 O₂(g) $\rarr$ SO₂(g) + SO₃(g)
D) SO₃(g) $\rarr$ S(s) + 3/2 O₂(g)
E) 2 S(s) + 3 O₂(g) $\rarr$ 2 SO₃(g)

Question 24

The reaction that represents the standard enthalpy of formation for sucrose (C₁₂H₂₂O₁₁) is:

A) C₁₂H₂₂O₁₁(s) + 12 O₂ $\rarr$ 12 CO₂(g) + 11 H₂O(g)
B) 12 C(diamond) + 11 H₂(g) + 11/2 O₂(g) $\rarr$ C₁₂H₂₂O₁₁(s)
C) 12 C(graphite) + 11 H₂(g) + 11/2 O₂(g) $\rarr$ C₁₂H₂₂O₁₁(s)
D) 24 C(diamond) + 22 H₂(g) + 11 O₂(g) $\rarr$ 2 C₁₂H₂₂O₁₁(s)
E) C₁₂H₂₂O₁₁(s) $\rarr$ 2 C(graphite) + 11 H₂(g) + 11/2 O₂(g)

Question 25

Butane (C₄H₁₀) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. Given $\Delta$ H ^$\circ$ _f[C₄H₁₀(g)] = -124.7 kJ/mol, $\Delta$ H ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol, $\Delta$ H ^$\circ$ _f[H₂O(g)] = -241.8 kJ/mol, how much energy is released (kJ) when 8.30 g of butane is burned

A) 22,100 kJ
B) 2,658.3 kJ
C) 379 kJ
D) 759 kJ
E) 2,910 kJ

Question 26

The reaction that represents the standard enthalpy of formation for acetone (CH₃COCH₃), a common ingredient in nail polish remover is:

A) 3 C(graphite) + 3 H₂(g) + ½ O₂(g) $\rarr$ CH₃COCH₃(l)
B) 6 C(diamond) + 6 H₂(g) + O₂(g) $\rarr$ 2 CH₃COCH₃(l)
C) 3 C(diamond) + 3 H₂(g) + ½ O₂(g) $\rarr$ CH₃COCH₃(l)
D) CH₃COCH₃(l) $\rarr$ 3 C(graphite) + 3 H₂(g) + ½ O₂(g)
E) CH₃COCH₃(l) + 4 O₂(g) $\rarr$ 3 CO₂(g) + 3 H₂O(g)

Question 27

Which of the following has a $\Delta$ H ^$\circ$ _f= 0 kJ/mol

A) CO₂(g)
B) O₃(g)
C) Cl^-(aq)
D) NH₃(aq)
E) I₂(s)

Question 28

The reaction that represents the standard enthalpy of formation for benzene (C₆H₆) is:

A) 6 C(diamond) + 3 H₂(g) $\rarr$ C₆H₆(l)
B) 6 C(graphite) + 6 H(g) $\rarr$ C₆H₆(l)
C) C₆H₆(l) + 15/2 O₂(g) $\rarr$ 6 CO₂(g) + 3 H₂O(g)
D) 6 C(graphite) + 3 H₂(g) $\rarr$ C₆H₆(l)
E) C₆H₆(l) $\rarr$ 6 C(graphite) + 3 H₂(g)

Question 29

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 ^$\circ$ C was observed. What is the heat capacity of the bomb calorimeter excluding the water

A) 1.76 kJ/ ^$\circ$ C
B) 3.64 kJ/ ^$\circ$ C
C) 7.8 kJ/ ^$\circ$ C
D) 15.3 kJ/ ^$\circ$ C
E) 32.9 kJ/ ^$\circ$ C

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 ^$\circ$ _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

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/ ^$\circ$ C. If the temperature rise of the calorimeter with water was 0.570 ^$\circ$ C, calculate the enthalpy of combustion of magnesium.Mg(s) + 1/2O₂(g) $\rarr$ MgO(s)

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

Question 32

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 ^$\circ$ _f) of NaF(s)

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

Question 33

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 ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol; $\Delta$ H ^$\circ$ _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 34

Octane (C₈H₁₈) undergoes combustion according to the following thermochemical equation: 2C₈H₁₈(l) + 25O₂(g) $\rarr$ 16CO₂(g) + 18H₂O(l), $\Delta$ H ^$\circ$ _rxn = -11,020 kJ/mol.Given that $\Delta$ H ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H ^$\circ$ _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 35

Acetylene (C₂H₂) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. Given $\Delta$ H ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol, $\Delta$ H ^$\circ$ _f[H₂O(g)] = -241.8 kJ/mol, and $\Delta$ H ^$\circ$ _f[C₂H₂(g)] = 226.6 kJ/mol, how much energy is released (kJ) when 10.5 moles of acetylene is burned

A) 2,510.8 kJ
B) 26,400 kJ
C) 13,200 kJ
D) 52,700 kJ
E) 9,050 kJ

Question 36

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 ^$\circ$ _rxn = -3857 kJ/mol
Given that $\Delta$ H ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol and $\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol, calculate the enthalpy of formation of glycine.

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

Question 37

Which of the following has a $\Delta$ H ^$\circ$ _f= 0 kJ/mol

A) NO(g)
B) CS₂(l)
C) Fe²⁺(aq)
D) H₂O(l)
E) N₂(g)

Question 38

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 ^$\circ$ C. Calculate $\Delta$ H per mole of HCl and NH₃ reacted.

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

Question 39

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 40

Which of the following processes is exothermic, given the following: N₂(g) + 2 O₂(g) $\rarr$ N₂O₄(l) $\Delta$ H ^$\circ$ = 9.67 kJ/mol
N₂(g) + 2 O₂(g) $\rarr$ 2 NO₂(g) $\Delta$ H ^$\circ$ = 67.70 kJ/mol

A) 2 N₂(g) + 4 O₂(g) $\rarr$ 2 N₂O₄(l)
B) ½ N₂(g) + O₂(g) $\rarr$ ½ N₂O₄(l)
C) N₂O₄(l) $\rarr$ N₂(g) + 2 O₂(g)
D) 2 N₂(g) + 4 O₂(g) $\rarr$ 2 NO₂(g) + N₂O₄(l)
E) 2 N₂(g) + 4 O₂(g) $\rarr$ 4 NO₂(g)

Question 41

Given that CaO(s) + H₂O(l) $\rarr$ Ca(OH)₂(s), $\Delta$ H ^$\circ$ _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

Calculate the standard enthalpy change for the reaction 2A + 2A₂ + 4AB + B $\rarr$ 5A₂B
Given: $\begin{array}{ll}2 \mathrm{~A}+\mathrm{B} \rightarrow \mathrm{~A}_{2} \mathrm{~B} & \Delta \mathrm{H}^{\circ}=-25.0 \mathrm{~kJ} / \mathrm{mol} \\2 \mathrm{~A}_{2} \mathrm{~B} \rightarrow 2 \mathrm{AB}+\mathrm{A}_{2} & \Delta \mathrm{H}^{\circ}=35.0 \mathrm{~kJ} / \mathrm{mol}\end{array}$

A) - 95.0 kJ/mol
B) - 60.0 kJ/mol
C) - 15.0 kJ/mol
D) 10.0 kJ/mol
E) 45.0 kJ/mol

Question 43

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 ^$\circ$ _rxn= -890.4 kJ/mol

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

Question 44

Calculate the standard enthalpy change for the reaction 4A + 2B $\rarr$ 2AB + A₂
Given: $\begin{array}{ll}2 \mathrm{~A}+\mathrm{B} \rightarrow \mathrm{~A}_{2} \mathrm{~B} & \Delta \mathrm{H}^{\circ}=-25.0 \mathrm{~kJ} / \mathrm{mol} \\2 \mathrm{~A}_{2} \mathrm{~B} \rightarrow 2 \mathrm{AB}+\mathrm{A}_{2} & \Delta \mathrm{H}^{\circ}=35.0 \mathrm{~kJ} / \mathrm{mol}\end{array}$

A) - 95.0 kJ/mol
B) - 60.0 kJ/mol
C) - 15.0 kJ/mol
D) 10.0 kJ/mol
E) 45.0 kJ/mol

Question 45

How much heat (kJ) is evolved when 4.50 g of Fe₂O₃ is reacted with excess carbon monoxide using the equation below?
Fe₂O₃(s) + 3CO(g) $\rarr$ 2 Fe(s) + 3 CO₂(g) $\Delta$ H ^$\circ$ _rxn = - 24.8 kJ/mol,

A) 0.699 kJ
B) 2.10 kJ
C) 17.9 kJ
D) 24.8 kJ
E) 112 kJ

Question 46

Calculate the standard enthalpy change for the reaction 2C₈H₁₈(l) + 17O₂(g) $\rarr$ 16CO(g) + 18H₂O(l).Given $\begin{array}{ll}2 \mathrm{C}_{8} \mathrm{H}_{18}(\mathrm{l})+25 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 16 \mathrm{CO}_{2}(\mathrm{g})+18 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) & \Delta \mathrm{H}^{\circ}=-11,020 \mathrm{~kJ} / \mathrm{mol} \\2 \mathrm{CO}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{g}) & \Delta \mathrm{H}^{\circ}=-566.0 \mathrm{~kJ} / \mathrm{mol}\end{array}$

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

Question 47

The combustion of butane produces heat according to the equation 2C₄H₁₀(g) + 13O₂(g) $\rarr$ 8CO₂(g) + 10H₂O(l), $\Delta$ H ^$\circ$ _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 48

The combustion of butane produces heat according to the equation 2C₄H₁₀(g) + 13O₂(g) $\rarr$ 8CO₂(g) + 10H₂O(l), $\Delta$ H ^$\circ$ _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 49

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 ^$\circ$ _rxn= -849 kJ/mol.

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

Question 50

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: $\begin{array}{ll}3 \mathrm{~S}(\mathrm{~s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \rightarrow 2 \mathrm{H}_{2} \mathrm{~S}(\mathrm{~g})+\mathrm{SO}_{2}(\mathrm{~g}) & \Delta \mathrm{H}^{\circ}=146.9 \mathrm{~kJ} / \mathrm{mol} \\\mathrm{~S}(\mathrm{~s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{SO}_{2}(\mathrm{~g}) & \Delta \mathrm{H}^{\circ}=-296.4 \mathrm{~kJ} / \mathrm{mol}\end{array}$

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 51

Calculate the standard enthalpy of formation of liquid methanol, CH₃OH(l), using the following information: $\begin{array}{ll}\mathrm{C} \text { (graph) }+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}(\mathrm{g}) & \Delta \mathrm{H}^{\circ}=-393.5 \mathrm{~kJ} / \mathrm{mol} \\\mathrm{H}_{2}(\mathrm{g})+(1 / 2) \mathrm{O}_{2} \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) & \Delta \mathrm{H}^{\circ}=-285.8 \mathrm{~kJ} / \mathrm{mol} \\\mathrm{CH}_{3} \mathrm{OH}(\mathrm{l})+(3 / 2) \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) & \Delta \mathrm{H}^{\circ}=-726.4 \mathrm{~kJ} / \mathrm{mol}\end{array}$

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

Question 52

The combustion of pentane produces heat according to the equation C₅H₁₂(l) + 8O₂(g) $\rarr$ 5CO₂(g) + 6H₂O(l), $\Delta$ H ^$\circ$ _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 53

Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l). Calculate $\Delta$ H_rxn for the combustion of 5.00 mol of B₅H₉.
$\Delta$ H ^$\circ$ _f[B₂O₃(s)] = -1,273.5 kJ/mol
$\Delta$ H ^$\circ$ _f[B₅H₉(s)] = 73.2 kJ/mol
$\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol

A) - 45,400 kJ
B) 45,400 kJ
C) - 22,700 kJ
D) - 9,090 kJ
E) - 8,790 kJ

Question 54

Given the thermochemical equation 2SO₂(g) + O₂(g) $\rarr$ 2SO₃(g), $\Delta$ H ^$\circ$ _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) 3.71 * 10³ kJ
E) 59,400 kJ

Question 55

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 ^$\circ$ C, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25 ^$\circ$ C.(Given: $\Delta$ H ^$\circ$ _f[CO₂(g)] = -393.5 kJ/mol, $\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol, $\Delta$ H ^$\circ$ _f[H₂O(g)] = -241.8 kJ/mol)

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

Question 56

Calculate the heat required when 2.50 mol of A reacts with excess B and A₂B according to the reaction: 2A + B + A₂B $\rarr$ 2AB + A₂
Given: $\begin{array}{ll}2 \mathrm{~A}+\mathrm{B} \rightarrow \mathrm{~A}_{2} \mathrm{~B} & \Delta \mathrm{H}^{\circ}=-25.0 \mathrm{~kJ} / \mathrm{mol} \\2 \mathrm{~A}_{2} \mathrm{~B} \rightarrow 2 \mathrm{AB}+\mathrm{A}_{2} & \Delta \mathrm{H}^{\circ}=35.0 \mathrm{~kJ} / \mathrm{mol}\end{array}$

A) 10.0 kJ
B) 12.5 kJ
C) 25.0 kJ
D) 35.0 kJ
E) 62.5 kJ

Question 57

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

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

Question 58

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

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

Question 59

Concerning the reaction $\mathrm{C} \text { (graphite) }+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g}) \quad \Delta \mathrm{H}^{\circ}=-393 \mathrm{~kJ} / \mathrm{mol}$ how many grams of C(graphite) must be burned to release 275 kJ of heat

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

Question 60

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 ^$\circ$ = -11,020 kJ/mol
2CO(g) + O₂(g) $\rarr$ 2CO₂(g) $\Delta$ H ^$\circ$ = -566.0 kJ/mol

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

Question 61

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

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

Question 62

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

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

Question 63

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

Question 64

Calcium oxide and water react in an exothermic reaction: CaO(s) + H₂O(l) $\rarr$ Ca(OH)₂(s), $\Delta$ H ^$\circ$ _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 65

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 66

The heat of solution of KCl is 17.2 kJ/mol and the lattice energy of KCl(s) is 701.2 kJ/mol. Calculate the total heat of hydration of 1.00 mol of gas phase K⁺ ions and Cl^- ions.

A) -718 kJ
B) -684 kJ
C) 684 kJ
D) 718 kJ
E) None of these.

Question 67

The total heat of hydration of 1.00 mol of gas phase Li⁺ ions and Cl ^- ions is -865 kJ. The lattice energy of LiCl(s) is 828 kJ/mol. Calculate the heat of solution of LiCl.

A) -1,693 kJ/mol
B) -37 kJ/mol
C) 37 kJ/mol
D) 1,693 kJ/mol

Question 68

At 25 ^$\circ$ 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 ^$\circ$ at 25 ^$\circ$ C for the reaction Na₂CO₃(s) + H₂O(l) $\rarr$ Na₂CO₃·H₂O(s).(Given: $\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol)

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

Question 69

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 ^$\circ$ C is mixed with 145 mL of 0.500 M NaOH, also at 23.15 ^$\circ$ C, what is 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· ^$\circ$ C, and that the density of the final solution is that of water.)

A) 20.24 ^$\circ$ C
B) 26.06 ^$\circ$ C
C) 29.19 ^$\circ$ C
D) 32.35 ^$\circ$ C
E) 36.57 ^$\circ$ C

Question 70

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 71

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 ^$\circ$ 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

Question 72

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 $~~~~~~~~~~~~~~\underline{q}~~~~~~~~~~~~~~\underline{w}~~~~~~~~~~~~~~\underline{\Delta{E}}$
A. $~~~\quad 250 \mathrm{~J} \quad-460 \mathrm{~J} \quad-210 \mathrm{~J}$
B. $\quad-250 \mathrm{~J} \quad-460 \mathrm{~J}~~~~-710 \mathrm{~J}$
C. $~~~\quad250 \mathrm{~J} \quad~~~~~ 460 \mathrm{~J} ~~~~~\quad 710 \mathrm{~J}$
D. $\quad-250 \mathrm{~J} \quad~~~~ 460 \mathrm{~J} ~~~~~~\quad 210 \mathrm{~J}$
E. $~~~\quad 250 \mathrm{~J} \quad-4.55 \mathrm{~J} \quad~~~~ 245 \mathrm{~J}$

A) A
B) B
C) C
D) D
E) E

Question 73

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 ^$\circ$ C is mixed with 300. mL of 0.250 M NaOH, also at 21.30 ^$\circ$ C, what is 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· ^$\circ$ C, and that the density of the final solution is that of water.)

A) 18.20 ^$\circ$ C
B) 24.40 ^$\circ$ C
C) 24.53 ^$\circ$ C
D) 34.25 ^$\circ$ C
E) 101.8 ^$\circ$ C

Question 74

For which of these reactions will the difference between $\Delta$ H ^$\circ$ and $\Delta$ E ^$\circ$ 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 75

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 ^$\circ$ C
(Given: $\Delta$ H ^$\circ$ _f[Na₂O₂(s)] = -510.9 kJ/mol; $\Delta$ H ^$\circ$ _f[NaOH(aq)] = -469.2 kJ/mol; $\Delta$ H ^$\circ$ _f[H₂O(l)] = -285.8 kJ/mol)

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

Question 76

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

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

Question 77

For which of these reactions will the difference between $\Delta$ H ^$\circ$ and $\Delta$ E ^$\circ$ 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 78

The heat of solution of LiCl is -37.1 kJ/mol, and the lattice energy of LiCl(s) is 828 kJ/mol. Calculate the total heat of hydration of 1.00 mol of gas phase Li⁺ ions and Cl^- ions.

A) -865 kJ
B) -791 kJ
C) 791 kJ
D) 865 kJ
E) None of these.

Question 79

10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H₂O at 18.0 ^$\circ$ C.If the following reaction occurs, what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat (The specific heat of water = 4.18 J/g· ^$\circ$ C)
CaO(s) + H₂O(l) $\rarr$ Ca(OH)₂(s) $\Delta$ H ^$\circ$ _rxn = -64.8 kJ/mol

A) 18.02 ^$\circ$ C
B) 35.8 ^$\circ$ C
C) 42.2 ^$\circ$ C
D) 117 ^$\circ$ C
E) 311 ^$\circ$ C

Question 80

Methanol (CH₃OH) burns according to the equation 2CH₃OH(l) + 3O₂(g) $\rarr$ 2CO₂(g) + 4H₂O(l), $\Delta$ H ^$\circ$ _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 * 10³ kJ
E) 3.41 * 10³ kJ