Deck 6: Thermochemistry

Question 1

Which of the following is true if ΔE_sys = -95 J?

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.

Answer 1

The system is losing 95 J,while the surroundings are gaining 95 J.

Question 2

Which of the following (with specific heat capacity provided)would show the smallest temperature change upon gaining 200.0 J of heat?

A)50.0 g Al,C_Al = 0.903 J/g°C
B)50.0 g Cu,C_Cu = 0.385 J/g°C
C)25.0 g granite,C_granite = 0.79 J/g°C
D)25.0 g Au,C_Au = 0.128 J/g°C
E)25.0 g Ag,C_Ag = 0.235 J/g°C

Answer 2

50.0 g Al,C_Al = 0.903 J/g°C

Question 3

Calculate the amount of heat (in kJ)necessary to raise the temperature of 47.8 g benzene by 57.0 K.The specific heat capacity of benzene is 1.05 J/g°C

A)1.61 kJ
B)16.6 kJ
C)2.59 kJ
D)2.86 kJ
E)3.85 kJ

Answer 3

2.86 kJ

Question 4

Calculate the amount of heat (in kJ)required to raise the temperature of a 79.0 g sample of ethanol from 298.0 K to 385.0 K.The specific heat capacity of ethanol is 2.42 J/g°C.

A)57.0 kJ
B)16.6 kJ
C)73.6 kJ
D)28.4 kJ
E)12.9 kJ

Question 5

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?

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

Question 6

A 4.98 g sample of aniline (C₆H₅NH₂,molar mass = 93.13 g/mol)was combusted in a bomb calorimeter with a heat capacity of 4.25 kJ/°C.If the temperature rose from 29.5°C to 69.8°C,determine the value of ΔH°_comb for aniline.

A)+7.81 × 10³ kJ/mol
B)-3.20 × 10³ kJ/mol
C)+1.71 × 10³ kJ/mol
D)-1.71 × 10³ kJ/mol
E)-7.81 × 10³ kJ/mol

Question 7

Determine the specific heat capacity of an alloy that requires 59.3 kJ to raise the temperature of 150.0 g alloy from 298 K to 398 K.

A)4.38 J/g°C
B)2.29 J/g°C
C)3.95 J/g°C
D)2.53 J/g°C
E)1.87 J/g°C

Question 8

A 21.8 g sample of ethanol (C₂H₅OH)is burned in a bomb calorimeter,according to the following reaction.If the temperature rises from 25.0 to 62.3°C,determine the heat capacity of the calorimeter.The molar mass of ethanol is 46.07 g/mol.
C₂H₅OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 3 H₂O(g)ΔH°_rxn = -1235 kJ

A)4.99 kJ/°C
B)5.65 kJ/°C
C)63.7 kJ/°C
D)33.1 kJ/°C
E)15.7 kJ/°C

Question 9

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?

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

Question 10

A piece of iron (C = 0.449 J/g°C)and a piece of gold (C = 0.128 J/g°C)have identical masses.If the iron has an initial temperature of 498 K and the gold has an initial temperature of 298 K,which of the following statements is TRUE of the outcome when the two metals are placed in contact with one another? Assume no heat is lost to the surroundings.

A)Since the two metals have the same mass,the final temperature of the two metals will be 398 K,exactly half way in between the two initial temperatures.
B)Since the two metals have the same mass,but the specific heat capacity of gold is much smaller than that of iron,the final temperature of the two metals will be closer to 298 K than to 498 K.
C)Since the two metals have the same mass,the thermal energy contained in the iron and gold after reaching thermal equilibrium will be the same.
D)Since the two metals have the same mass,but the specific heat capacity of iron is much greater than that of gold,the final temperature of the two metals will be closer to 498 K than to 298 K.
E)None of the above are true.

Question 11

Calculate the change internal energy (ΔE)for a system that is giving off 45.0 kJ of heat and is performing 855 J of work on the surroundings.

A)44.1 kJ
B)-44.1 kJ
C)-45.9 kJ
D)9.00 × 10² kJ
E)-9.00 × 10² kJ

Question 12

A sample of copper absorbs 43.6 kJ of heat,resulting in a temperature rise of 75.0°C,determine the mass (in kg)of the copper sample if the specific heat capacity of copper is 0.385 J/g°C.

A)1.51 kg
B)6.62 kg
C)1.26 kg
D)7.94 kg
E)3.64 kg

Question 13

For ?E_sys to always be -,what must be true?

A)q = w
B)+q > -w
C)+w > -q
D)-w > +q

Question 14

A 6.55 g sample of aniline (C₆H₅NH₂,molar mass = 93.13 g/mol)was combusted in a bomb calorimeter.If the temperature rose by 32.9°C,use the information below to determine the heat capacity of the calorimeter.
4 C₆H₅NH₂(l)+ 35 O₂(g)→ 24 CO₂(g)+ 14 H₂O(g)+ 4 NO₂(g)
ΔH°_rxn= -1.28 × 10⁴ kJ

A)97.3 kJ/°C
B)38.9 kJ/°C
C)5.94 kJ/°C
D)6.84 kJ/°C
E)12.8 kJ/°C

Question 15

Calculate the change in internal energy (ΔE)for a system that is giving off 25.0 kJ of heat and is changing from 12.00 L to 6.00 L in volume at 1.50 atm pressure.(Remember that 101.3 J = 1 L^∙atm)

A)+25.9 kJ
B)-16.0 kJ
C)-25.9 kJ
D)-24.1 kJ
E)937 kJ

Question 16

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

A)10.0 g Ag,C_Ag = 0.235 J/g°C
B)10.0 g H₂O,C_H2O = 4.18 J/g°C
C)10.0 g ethanol,C_ethanol = 2.42 J/g°C
D)10.0 g Fe,C_Fe = 0.449 J/g°C
E)10.0 g Au,C_Au = 0.128 J/g°C

Question 17

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

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

Question 18

Calculate the change in internal energy (ΔE)for a system that is absorbing 35.8 kJ of heat and is expanding from 8.00 to 24.0 L in volume at 1.00 atm.(Remember that 101.3 J = 1 L^∙atm)

A)+51.8 kJ
B)-15.8 kJ
C)-16.6 kJ
D)-29.3 kJ
E)+34.2 kJ

Question 19

Determine the final temperature of a gold nugget (mass = 376 g)that starts at 398 K and loses 4.85 kJ of heat to a snowbank when it is lost.The specific heat capacity of gold is 0.128 J/g°C.

A)133 K
B)398 K
C)187 K
D)297 K
E)377 K

Question 20

A sample of 5.23 kg of aluminum absorbs heat,which raises the temperature 50.0°C.Determine the amount of heat absorbed,in kJ,if the specific heat capacity of aluminum is 0.903 J/g°C.

A)0.0405 kJ
B)290 kJ
C)236 kJ
D)8.60 kJ

Question 21

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.
Fe₃O₄(s)→ 3 Fe(s)+ 2 O₂(g)ΔH°_rxn = +1118 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 22

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

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

Question 23

How much energy is evolved during the reaction of 48.7 g of Al,according to the reaction below? Assume that there is excess Fe₂O₃.
Fe₂O₃(s)+ 2 Al(s)→ Al₂O₃(s)+ 2 Fe(s)ΔH°_rxn = -852 kJ

A)415 kJ
B)207 kJ
C)241 kJ
D)130 kJ
E)769 kJ

Question 24

A 35.6 g sample of ethanol (C₂H₅OH)is burned in a bomb calorimeter,according to the following reaction.If the temperature rose from 35.0 to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ/°C,what is the value of ΔH°_rxn? The molar mass of ethanol is 46.07 g/mol.
C₂H₅OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 3 H₂O(g)ΔH°_rxn = ?

A)-1.24 × 10³ kJ/mol
B)+1.24 × 10³ kJ/mol
C)-8.09 × 10³ kJ/mol
D)-9.55 × 10³ kJ/mol
E)+9.55 × 10³ kJ/mol

Question 25

The temperature rises from 25.00 °C to 29.00 °C in a bomb calorimeter when 3.50 g of sucrose undergoes combustion in a bomb calorimeter.Calculate ΔE_rxn for the combustion of sucrose in kJ/mol sucrose.The heat capacity of the calorimeter is 4.90 kJ/°C .The molar mass of sugar is 342.3 g/mol.

A)(^)- 1.92 × 10³ kJ/mole
B)1.92 × 10³ kJ/mole
C)(^)- 1.23 × 10³ kJ/mole
D)2.35 × 10⁴ kJ/mole

Question 26

According to the following thermochemical equation,what mass of H₂O (in g)must form in order to produce 975 kJ of energy?
SiO₂(s)+ 4 HF(g)→ SiF₄(g)+ 2 H₂O(l)ΔH°_rxn = -184 kJ

A)68.0 g
B)102 g
C)54.1 g
D)191 g
E)95.5 g

Question 27

What volume of benzene (C₆H₆,d= 0.88 g/mL,molar mass = 78.11 g/mol)is required to produce 1.5 x 10³ kJ of heat according to the following reaction?
2 C₆H₆(l)+ 15 O₂(g)→ 12 CO₂(g)+ 6 H₂O(g)ΔH°_rxn = -6278 kJ

A)75 mL
B)37 mL
C)21 mL
D)19 mL
E)42 mL

Question 28

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/mol.
B₂H₆(g)+ 6 Cl₂(g)→ 2 BCl₃(g)+ 6 HCl(g)ΔH°_rxn = -1396 kJ

A)58.7 kJ
B)156 kJ
C)215 kJ
D)352 kJ
E)508 kJ

Question 29

What is the minimum energy required to decompose 765 g of PCl₃,according to the reaction below? The molar mass of PCl₃ is 137.32 g/mol and may be useful.
4 PCl₃(g)→ P₄(s)+ 6 Cl₂(g)ΔH°_rxn = +1207 kJ

A)2.31 × 10³ kJ
B)4.33 × 103 kJ
C)6.72 × 10³ kJ
D)1.68 × 10³ kJ
E)5.95 × 10³ kJ

Question 30

Using the following equation for the combustion of octane,calculate the heat of reaction for 100.0 g of octane.The molar mass of octane is 114.33 g/mole.
2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O ΔH°_rxn = -11018 kJ

A)-4.82 x 10³ kJ
B)-4.82 kJ
C)-9.64 × 10³ kJ
D)-1.26 × 10⁴ kJ

Question 31

Which of the following processes is endothermic?

A)the freezing of water
B)the combustion of propane
C)a hot cup of coffee (system)cooling on a countertop
D)the chemical reaction in a "hot pack" often used to treat sore muscles
E)the vaporization of rubbing alcohol

Question 32

Which of the following processes is endothermic?

A)An atom emits a photon.
B)the condensation of water
C)An atom absorbs a photon.
D)the electron affinity of a fluorine atom
E)None of the above processes are endothermic.

Question 33

Given w = 0,an endothermic reaction has the following.

A)+ΔH and -ΔE
B)-ΔH and +ΔE
C)+ΔH and +ΔE
D)-ΔH and -ΔE

Question 34

According to the following thermochemical equation,what mass of HF (in g)must react in order to produce 345 kJ of energy? Assume excess SiO₂.
SiO₂(s)+ 4 HF(g)→ SiF₄(g)+ 2 H₂O(l)ΔH°_rxn = -184 kJ

A)42.7 g
B)37.5 g
C)150.g
D)107 g
E)173 g

Question 35

A 12.8 g sample of ethanol (C₂H₅OH)is burned in a bomb calorimeter with a heat capacity of 5.65 kJ/°C.Using the information below,determine the final temperature of the calorimeter if the initial temperature is 25.0°C.The molar mass of ethanol is 46.07 g/mol.
C₂H₅OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 3 H₂O(g)ΔH°_rxn = -1235 kJ

A)53.4°C
B)28.1°C
C)111°C
D)85.7°C
E)74.2°C

Question 36

A 6.55 g sample of aniline (C₆H₅NH₂,molar mass = 93.13 g/mol)was combusted in a bomb calorimeter with a heat capacity of 14.25 kJ/°C.If the initial temperature was 32.9°C,use the information below to determine the value of the final temperature of the calorimeter.
4 C₆H₅NH₂(l)+ 35 O₂(g)→ 24 CO₂(g)+ 14 H₂O(g)+ 4 NO₂(g)
ΔH°_rxn = -1.28 × 10⁴ kJ

A)257°C
B)46.6°C
C)48.7°C
D)41.9°C
E)931°C

Question 37

An exothermic reaction has

A)a negative ΔH and absorbs heat from the surroundings.An exothermic reaction feels warm to the touch.
B)a positive ΔH and absorbs heat from the surroundings.An exothermic reaction feels warm to the touch.
C)a positive ΔH and gives off heat to the surroundings.An exothermic reaction feels warm to the touch.
D)a negative ΔH and gives off heat to the surroundings.An exothermic reaction feels warm to the touch.

Question 38

Which of the following processes is exothermic?

A)the formation of dew in the morning
B)the melting of ice
C)the chemical reaction in a "cold pack" often used to treat injuries
D)the vaporization of water
E)None of the above are exothermic.

Question 39

How much energy is evolved during the formation of 98.7 g of Fe,according to the reaction below?
Fe₂O₃(s)+ 2 Al(s)→ Al₂O₃(s)+ 2 Fe(s)ΔH°_rxn = -852 kJ

A)753 kJ
B)1.51 × 10³ kJ
C)4.20 × 10³ kJ
D)482 kJ
E)241 kJ

Question 40

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.
B₂H₆(g)+ 6 Cl₂(g)→ 2 BCl₃(g)+ 6 HCl(g)ΔH°_rxn = -1396 kJ

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

Question 41

Use the standard reaction enthalpies given below to determine ΔH°_rxn for the following reaction:
P₄(g)+ 10 Cl₂(g)→ 4PCl₅(s)ΔH°_rxn = ?
Given:
PCl₅(s)→ PCl₃(g)+ Cl₂(g)ΔH°_rxn= +157 kJ
P₄(g)+ 6 Cl₂(g)→ 4 PCl₃(g)ΔH°_rxn = -1207 kJ

A)-1835 kJ
B)-1364 kJ
C)-1050.kJ
D)-1786 kJ
E)-2100.kJ

Question 42

Which of the following statements is true?

A)State functions do not depend on the path taken to arrive at a particular state.
B)DE_rxn can be determined using constant volume calorimetry.
C)Energy is neither created nor destroyed,excluding nuclear reactions.
D)ΔH_rxn can be determined using constant pressure calorimetry.
E)All of the above are true.

Question 43

Use the ΔH°_f information provided to calculate ΔH°_rxn for the following:
ΔH°_{f (kJ/mol)} SO₂Cl₂(g)+ 2 H₂O(l)→ 2 HCl(g)+ H₂SO4(l)ΔH°_rxn = ?
SO₂Cl₂(g)-364
H₂O(l)-286
HCl(g)-92
H₂SO₄(l)-814

A)-256 kJ
B)+161 kJ
C)-62 kJ
D)+800.kJ
E)-422 kJ

Question 44

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/g°C and water = 4.18 J/g°C.

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

Question 45

Use the information provided to determine ΔH°_rxn for the following reaction:
ΔH°_f (kJ/mol)3 Fe₂O₃(s)+ CO(g)→ 2 Fe₃O₄(s)+ CO₂(g)ΔH°_rxn = ? kJ
Fe₂O₃(s)-824
Fe₃O₄(s)-1118
CO(g)-111
CO₂(g)-394

A)+277 kJ
B)-577 kJ
C)-47 kJ
D)+144 kJ
E)-111 kJ

Question 46

A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO₃ in a coffee cup calorimeter.If both solutions were initially at 35.00°C and the temperature of the resulting solution was recorded as 37.00°C,determine the ΔH°_rxn (in units of kJ/mol NaOH)for the neutralization reaction between aqueous NaOH and HCl.Assume 1)that no heat is lost to the calorimeter or the surroundings,and 2)that the density and the heat capacity of the resulting solution are the same as water.

A)-55.7 kJ/mol NaOH
B)-169 kJ/mol NaOH
C)-16.7 kJ/mol NaOH
D)-27.9 kJ/mol NaOH
E)- 34.4 kJ/mol NaOH

Question 47

Use the information provided to determine ΔH°_rxn for the following reaction:
ΔH°_f (kJ/mol)CH₄(g)+ 3 Cl₂(g)→ CHCl₃(l)+ 3 HCl(g)ΔH°_rxn = ?
CH₄(g)-75
CHCl₃(l)-134
HCl(g)-92

A)-151 kJ
B)-335 kJ
C)+662 kJ
D)+117 kJ
E)-217 kJ

Question 48

Use the information provided to determine ΔH°_rxn for the following reaction:
ΔH°_f (kJ/mol)CH₄(g)+ 4 Cl₂(g)→ CCl₄(g)+ 4 HCl(g)ΔH°_rxn = ?
CH₄(g)-75
CCl₄(g)-96
HCl(g)-92

A)-389 kJ
B)-113 kJ
C)+113 kJ
D)-71 kJ
E)+79 kJ

Question 49

Use the standard reaction enthalpies given below to determine ΔH°_rxn for the following reaction:
2 S(s)+ 3 O₂(g)→ 2SO₃(g)ΔH°_rxn = ?
Given:
SO₂(g)→ S(s)+ O₂(g)ΔH°_rxn = +296.8 kJ
2 SO₂(g)+ O₂(g)→ 2 SO₃(g)ΔH°_rxn = -197.8 kJ

A)-494.6 kJ
B)-692.4 kJ
C)-791.4 kJ
D)-98.8 kJ
E)-293.0 kJ

Question 50

Which of the following statements are false?

A)If a chemical equation is multiplied by some factor,ΔH°_rxn is also multiplied by the same factor.
B)If a chemical reaction changes direction,then ΔH°_rxn changes sign.
C)If a chemical equation can be expressed as the sum of a series of steps,ΔH°_rxn for the overall equation is the sum of the heats of reactions for each step.
D)Standard states are all in the gas phase.

Question 51

Match the following.
+w

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

Question 52

Use the ΔH°_f and ΔH°_rxn information provided to calculate ΔH°_f for IF:
ΔH°_{f (kJ/mol)} IF₇(g)+ I₂(g)→ IF₅(g)+ 2 IF(g)ΔH°_rxn = -89 kJ
IF₇(g)-941
IF₅(g)-840

A)101 kJ/mol
B)-146 kJ/mol
C)-190.kJ/mol
D)-95 kJ/mol
E)24 kJ/mol

Question 53

Match the following.
-w

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

Question 54

Which of the following processes is 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 ΔH^∘_f for an ionic compound
E)All of the above processes are exothermic.

Question 55

Choose the reaction that illustrates ΔH°_f for Ca(NO₃)₂.

A)Ca(s)+ N₂(g)+ 3O₂(g)→ Ca(NO₃)₂(s)
B)Ca²⁺(aq)+ 2 NO₃^-(aq)→ Ca(NO₃)₂(aq)
C)Ca(s)+ 2 N(g)+ 6 O(g)→ Ca(NO₃)₂(s)
D)Ca(NO₃)₂(aq)→ Ca²⁺(aq)+ 2 NO₃^-(aq)
E)Ca(NO₃)₂(s)→ Ca(s)+ N₂(g)+ 3O₂(g)

Question 56

Two aqueous solutions are both at room temperature and are then mixed in a coffee cup calorimeter.The reaction causes the temperature of the resulting solution to fall below room temperature.Which of the following statements is true?

A)The products have a lower potential energy than the reactants.
B)This type of experiment will provide data to calculate ΔE_rxn.
C)The reaction is exothermic.
D)Energy is leaving the system during reaction.
E)None of the above statements are true.

Question 57

Use the standard reaction enthalpies given below to determine ΔH°_rxn for the following reaction:
2 NO(g)+ O₂(g)→ 2 NO₂(g)ΔH°_rxn = ?
Given:
N₂(g)+ O₂(g)→ 2 NO(g)ΔH°_rxn = +183 kJ
1/2 N₂(g)+ O₂(g)→ NO₂(g)ΔH°_rxn = +33 kJ

A)-150.kJ
B)-117 kJ
C)-333 kJ
D)+115 kJ
E)+238 kJ

Question 58

Use the ΔH°_f and ΔH°_rxn information provided to calculate ΔH°_f for SO₃(g):
ΔH°_{f (kJ/mol)} 2 SO₂(g)+ O₂(g)→ 2 SO₃(g)ΔH°_rxn = -198 kJ
SO₂(g)-297

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

Question 59

Choose the thermochemical equation that illustrates ΔH°_f for Li₂SO₄.

A)2 Li⁺(aq)+ SO₄^2-(aq)→ Li₂SO₄(aq)
B)2 Li(s)+ 1/8 S₈(s,rhombic)+ 2 O₂(g)→ Li₂SO₄(s)
C)Li₂SO₄(aq)→ 2 Li⁺(aq)+ SO₄^2-(aq)
D)8 Li₂SO₄(s)→ 16 Li(s)+ S₈(s,rhombic)+ 16 O₂(g)
E)16 Li(s)+ S₈(s,rhombic)+ 16 O₂(g)→ 8 Li₂SO₄(s)

Question 60

Match the following.
-ΔE

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

Question 61

Explain the difference between ΔH and ΔE.

Question 62

A 6.50-g sample of copper metal at 25.0°C is heated by the addition of 84.0 J of energy.The final temperature of the copper is ________°C.The specific heat capacity of copper is 0.38 J/g ∙ K.

A)29.9
B)25.0
C)9.0
D)59.0
E)34.0

Question 63

The specific heat capacity of liquid water is 4.18 J/g ∙ K.How many joules of heat are needed to raise the temperature of 5.00 g of water from 25.1°C to 65.3°C?

A)48.1 J
B)840 J
C)1.89 ×
J
D)2.08 ×
J
E)54.4 J

Question 64

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

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

Question 65

Give the equation to calculate the enthalpy of a system.

Question 66

A 5.00-g sample of liquid water at 25.0 C is heated by the addition of 84.0 J of energy.The final temperature of the water is ________ °C.The specific heat capacity of liquid water is 4.18 J/g ∙ K.

A)95.2
B)25.2
C)-21.0
D)29.0
E)4.02

Question 67

For a process at constant pressure,49,600 calories of heat are released.This quantity of heat is equivalent to

A)4.82 × 10^-6 J.
B)1.19 × 10⁴ J.
C)1.24 × 10⁴ J.
D)2.08 × 10⁵ J.

Question 68

Calculate the work,w,gained or lost by the system when a gas expands from 15 L to 40 L against a constant external pressure of 1.5 atm.1 L ∙ atm = 101 J.

A)-6.1 kJ
B)-3.8 kJ
C)+3.8 kJ
D)+6.1 kJ

Question 69

Match the following.
+q

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

Question 70

Match the following.
-q

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

Question 71

The specific heat capacity of liquid mercury is 0.14 J/g ∙ K.How many joules of heat are needed to raise the temperature of 5.00 g of mercury from 15.0°C to 36.5°C?

A)7.7 × 10² J
B)15 J
C)36 J
D)0.0013 J
E)1.7 J

Question 72

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

Question 73

Describe the energy changes that occur when a book is held 6 ft off the floor and then dropped.

Question 74

Define chemical energy.

Question 75

Give the temperature and pressure for the standard state for a liquid.

Question 76

It takes 11.2 kJ of energy to raise the temperature of 145 g of benzene from 23.0°C to 68.0°C.What is the specific heat of benzene?

A)1.14 J/(g ∙ °C)
B)1.72 J/(g ∙ °C)
C)3.48 J/(g ∙ °C)
D)5.25 J/(g ∙ °C)

Question 77

The specific heat of copper is 0.385 J/(g ∙ °C).If 34.2 g of copper,initially at 24.0°C,absorbs 4.689 kJ,what will be the final temperature of the copper?

A)24.4°C
B)26.8°C
C)356°C
D)380°C

Question 78

Where does the energy absorbed during an endothermic reaction go?

Question 79

The specific heat capacity of methane gas is 2.20 J/g ∙ K.How many joules of heat are needed to raise the temperature of 5.00 g of methane from 36.0°C to 75.0°C?

A)88.6 J
B)429 J
C)1221 J
D)0.0113 J
E)22.9 J

Question 80

The specific heat capacity of solid copper metal is 0.385 J/g ∙ K.How many joules of heat are needed to raise the temperature of a 1.55-kg block of copper from 33.0°C to 77.5°C?

A)1.79 × 10⁵ J
B)26.6 J
C)2.66 × 10⁴ J
D)5.58 × 10^-6 J
E)0.00558 J