Deck 6: Energy and Chemical Reactions

Question 1

Which substance has the highest molar heat capacity?

A) copper (specific heat = 0.385 J g^-1 °C^-1)
B) iron (specific heat = 0.451 J g^-1 °C^-1)
C) silver (specific heat = 0.232 J g^-1 °C^-1)
D) lead (specific heat = 0.128 J g^-1 °C^-1)
E) aluminum (specific heat = 0.902 J g^-1 °C^-1)

Answer 1

lead (specific heat = 0.128 J g^-1 °C^-1)

Question 2

Which of the following is an example of potential energy?

A) holding a baseball
B) running around bases
C) pitching a baseball
D) swinging a bat
E) sliding into home plate

Answer 2

holding a baseball

Question 3

Which property can be used to distinguish one substance from another substance?

A) specific heat capacity
B) kinetic energy
C) temperature
D) enthalpy
E) internal energy

Answer 3

specific heat capacity

Question 4

How many joules are there in one glass of milk containing 110 Calories?

A) 4.6 × 10⁵ J
B) 460 kJ
C) 2.6 × 10⁴ J
D) 26 J
E) 0.46 J

Question 5

Determine if each of the four situations below describes kinetic or potential energy.
I. the bonds in propane molecules
II. a reservoir of water behind a dam
III. water molecules colliding into each other
IV. the electrical current in a light bulb that is turned on

A)
B)
C)
D)
E)

Question 6

How many kilojoules are there in 150 Calories of popcorn?

A) 3.6 × 10^-2 kJ
B) 36 kJ
C) 630 kJ
D) 3.6 × 10⁴ kJ
E) 6.3 × 10⁵ kJ

Question 7

Determine the quantity of ice required to absorb exactly 50 kJ of energy when the ice warms from -50.0°C to -10.0°C (specific heat of ice = 2.06 J g^-1 °C^-1).

A) 0.485 g
B) 0.607 g
C) 485 g
D) 607 g
E) 2.43 × 10³ g

Question 8

Determine the incorrect relationship given below.

A) 1 µJ = 1 × 10^-6 J
B) 1000 cal = 1 kcal
C) 44.0 kJ = 1.05 × 10⁴ cal
D) 1000 J = 1 kJ
E) 80.0 cal/g = 312 J/g

Question 9

Determine the amount of heat required to raise the temperature of a 153 g bar of gold by 50.0°C (specific heat of gold = 0.128 J g^-1 °C^-1).

A) 490 J
B) 979 J
C) 1.47 × 10³ J
D) 7.65 × 10³ J
E) 5.98 × 10⁴ J

Question 10

The temperature of a 21.6 g sample of a metal rises 6.04°C when 58.8 J of energy is applied to it. What is the identity of the metal?

A) silver (specific heat = 0.232 J g^-1 °C^-1)
B) copper (specific heat = 0.385 J g^-1 °C^-1)
C) iron (specific heat = 0.451 J g^-1 °C^-1)
D) lead (specific heat = 0.128 J g^-1 °C^-1)
E) aluminum (specific heat = 0.902 J g^-1 °C^-1)

Question 11

What is the molar heat capacity of aluminum (specific heat = 0.902 J g^-1 °C^-1)?

A) 0.034 J mol^-1 °C^-1
B) 24.8 J mol^-1 °C^-1
C) 29.3 J mol^-1 °C^-1
D) 120 J mol^-1 °C^-1
E) 1.5 × 10²⁵ J mol^-1 °C^-1

Question 12

The First Law of Thermodynamics states that:

A) Molecules move faster as temperature increases.
B) The total entropy of the universe is increasing.
C) Energy transfers from hotter objects to cooler objects.
D) Samples with different temperatures that come in contact with one another will reach thermal equilibrium.
E) The total energy of the universe is constant.

Question 13

Heating a 50.0 g sample of iron (specific heat = 0.451 J g^-1 °C^-1) raises its temperature from 25.0°C to 79.4°C. How much energy was required to heat the sample?

A) 0.414 J
B) 2.41 J
C) 564 J
D) 1230 J
E) 1790 J

Question 14

A 20.0 g sample of aluminum (specific heat = 0.902 J g^-1 °C^-1) with an initial temperature of 48.6°C is heated with 427 J of energy. What is the final temperature of the sample?

A) 74.8°C
B) 72.3°C
C) 26.2°C
D) 24.9°C
E) 23.7°C

Question 15

Which statement about energy is false?

A) Thermodynamics is the science of working and heating processes.
B) Working and heating are processes that transfer energy.
C) Chemical reactions are processes that transfer energy
D) The chemical energy of foods and fuels is a type of potential energy.
E) The thermal energy of nanoscale objects is a type of potential energy.

Question 16

How much energy is required to raise the temperature of 200.0 g of water by 25.0°C? The specific heat of water = 4.184 J g^-1 °C^-1.

A) 20.9 kJ
B) 9.36 kJ
C) 10.5 kJ
D) 210 kJ
E) 1200 kJ

Question 17

Heating a 25.0 g sample of each substance below with 375 J of energy will cause which substance to have the greatest increase in temperature?

A) copper (specific heat = 0.385 J g^-1 °C^-1)
B) gold (specific heat = 0.128 J g^-1 °C^-1)
C) iron (specific heat = 0.451 J g^-1 °C^-1)
D) water (specific heat = 4.184 J g^-1 °C^-1)
E) Not enough information to determine.

Question 18

Which of the following is not an example of kinetic energy?

A) the motion of a molecule
B) a golf ball sitting on a tee
C) the vibration of an object
D) a brick falling from the top of a building
E) the motion of electrons through a wire

Question 19

Which of the following is an example of potential energy?

A) atoms vibrating back and forth around a specific location
B) a rock rolling down a mountain
C) a fat molecule stored in the body
D) electrons flowing through an electrical conductor
E) the sound of a dog barking

Question 20

What is the molar heat capacity of table salt, NaCl (specific heat = 0.88 J g^-1 °C^-1)?

A) 5.30 × 10²² J mol^-1 °C^-1
B) 24.6 J mol^-1 °C^-1
C) 51.4 J mol^-1 °C^-1
D) 117 J mol^-1 °C^-1
E) 245 J mol^-1 °C^-1

Question 21

Based on the following thermochemical equation below, which statement is false?

A) For the reverse process, DH° = + 46.11 kJ.
B) The value of 46.11 kJ applies to the formation of two moles of NH₃.
C) The value of 92.22 kJ applies to the reaction of two moles of N₂ and three moles of H₂.
D) Per mole of N₂, DH° = -46.11 kJ.
E) Per mole of H₂, DH° = -15.37 kJ.

Question 22

The temperature of 3.50 kg of water is raised by 1.17°C when 1.00 g of hydrazine N₂H₄ is burned in a bomb calorimeter. The calorimeter has a heat capacity of 883 J/°C. How much heat is given off by the sample? The specific heat of water = 4.184 J g^-1 °C^-1.

A) 0.944 kJ
B) 16.3 kJ
C) 17.1 kJ
D) 18.2 kJ
E) 21.5 kJ

Question 23

Determine the heat of reaction for the process

using the information given below:

A) -1074.0 kJ
B) -22.0 kJ
C) 22.2 kJ
D) 249.8 kJ
E) 1074.0 kJ

Question 24

What is the enthalpy change for the combustion of 4.73 g C₄H₁₀ in excess oxygen?

A) -23200 kJ
B) -8960 kJ
C) -401 kJ
D) -154 kJ
E) -32.7 kJ

Question 25

A 0.100 mole sample of CH₄ reacts completely in a calorimeter having a heat capacity of 783 J/°C. The calorimeter contains 254 g of water. Determine the temperature increase of the calorimeter. The specific heat of water = 4.184 J g^-1 °C^-1.

A) 4.35 × 10^-3°C
B) 7.56°C
C) 10.2°C
D) 31.6°C
E) 43.5°C

Question 26

How much energy is required to melt 10.0 g of ice at 0.0°C, warm it to 100.0°C and completely vaporize the sample? The enthalpy of fusion of ice = 333 J g^-1 at 0 °C; the specific heat of water = 4.184 J g^-1 °C^-1; the heat of vaporization of water = 2260 J g^-1 at 100 °C.

A) 30100 J
B) 22600 J
C) 4180 J
D) 3330 J
E) 343 J

Question 27

Which process is exothermic?

A) freezing rain drops
B) evaporating alcohol
C) defrosting frozen food
D) warming milk
E) subliming dry ice

Question 28

What is the enthalpy change when 22.5 g of CH₄ are burned in excess O₂?

A) -39.5 kJ
B) -890 kJ
C) -1250 kJ
D) +890 kJ
E) +1250 kJ

Question 29

A bomb calorimeter has a heat capacity of 675 J/°C and contains 925 g of water. If the combustion of 0.500 mole of a hydrocarbon increases the temperature of the calorimeter from 24.26°C to 53.88°C, determine the enthalpy change per mole of hydrocarbon. The specific heat of water = 4.184 J g^-1 °C^-1.

A) -94.8 kJ
B) -135 kJ
C) -229 kJ
D) -269 kJ
E) -802 kJ

Question 30

How much heat is required to melt 125 g of ice at 0°C? The enthalpy of fusion of ice = 333 J g^-1 at 0 °C.

A) 0.375 J
B) 41.6 kJ
C) 283 kJ
D) 333 J
E) 523 J

Question 31

Determine if each of the four processes below describes positive or negative changes to the internal energy of the system.
I. water absorbs heat from the surroundings and becomes steam
II. steam expands and pushes against the surrounding air
III. fuel molecules burn and heat the surroundings
IV. air is compressed into an inner tube by an external pump

A)
B)
C)
D)
E)

Question 32

The complete combustion of 1.47 g of methanol produces 29.3 kJ of heat. Determine the DH° for the reaction and its sign.

A) -938 kJ
B) -638 kJ
C) -1.35 kJ
D) +638 kJ
E) +938 kJ

Question 33

When does an endothermic reaction occur?

A) when the enthalpy of the reactants is greater than the enthalpy of the products
B) when bonds are formed
C) when the energy of bonds breaking is greater than the energy of bonds formed
D) when the energy of bonds breaking is less than the energy of bonds formed
E) when stronger bonds are formed and weaker bonds are broken

Question 34

Which term refers to a quantity of heat transferred at constant pressure?

A) work
B) specific heat capacity
C) expansion
D) entropy
E) enthalpy

Question 35

Based on the following thermochemical equation, which statement is false?

A) The thermochemical equation represents a physical change.
B) The enthalpy change for the gas condensing into a liquid is known.
C) The internal energy of the surroundings increases.
D) The pressure for the process is known.
E) The enthalpy change is endothermic.

Question 36

A sample of water containing 2.00 moles is initially at 30.0°C. If the sample absorbs 2.00 kJ of heat, what is the final temperature of the water? (specific heat of water = 4.184 J g^-1 °C^-1)

A) 13.3°C
B) 30.2°C
C) 43.3°C
D) 46.7°C
E) 269°C

Question 37

What is the enthalpy change when 175 g of C₃H₈ are burned in excess O₂?

A) -1.71 × 10⁷ kJ
B) -1.79 × 10^-3 kJ
C) -3.47 × 10⁰ kJ
D) -3.89 × 10⁵ kJ
E) -8.82 × 10³ kJ

Question 38

Determine the heat of reaction for the process

using the information given below:

A) -295.3 kJ
B) -29.2 kJ
C) +29.2 kJ
D) +295.3 kJ
E) +398.4 kJ

Question 39

Which of the following statements is false?

A) Breaking bonds is always endothermic.
B) Bond enthalpies quantify the energy change for the complete separation of two bonded atoms in a molecule at constant pressure.
C) Bond enthalpy values are based on molecules in the gas phase.
D) Breaking weak bonds and making an equal number of strong bonds is exothermic.
E) Breaking weak bonds and making a greater number of equally weak bonds is endothermic.

Question 40

A bomb calorimeter has a heat capacity of 783 J/°C and contains 254 g of water. How much energy is evolved or absorbed when the temperature of the calorimeter goes from 23.73°C to 26.01°C? The specific heat of water = 4.184 J g^-1 °C^-1.

A) 1.78 kJ evolved
B) 2.42 kJ evolved
C) 4.21 kJ evolved
D) 2420 kJ absorbed
E) 4210 kJ evolved

Question 41

Determine the heat of reaction for the process
using the information given below:

A) -320.1 kJ
B) -233.7 kJ
C) 233.7 kJ
D) 320.1 kJ
E) 504.7 kJ

Question 42

According to the First Law of Thermodynamics, the total _____________ of the universe is constant.

Question 43

The quantity of energy required to increase the temperature of one gram of a sample by 1°C is called the _____________.

Question 45

Enthalpy change is equal to heat transfer at constant _______________.

Question 46

The standard enthalpies of formation for several substances are given below: Determine the DH° for the reaction below.

A) -366.4 kJ
B) -299.9 kJ
C) -298.5 kJ
D) -255.9 kJ
E) 255.9 kJ

Question 47

How much energy in kilojoules is required to raise the temperature of 20.0 g of water from 22.0°C to 37.0°C? The specific heat of water = 4.184 J g^-1 °C^-1.

Question 48

The standard enthalpies of formation for several substances are given below: Calculate the DH° for the reaction below.

A) -881.4 kJ
B) -811.8 kJ
C) -149.6 kJ
D) +149.6 kJ
E) +213.4 kJ

Question 49

The standard enthalpies of formation for several substances are given below: Determine the DH° for the reaction below.

A) -2322.5 kJ
B) -2219.9 kJ
C) -782.8 kJ
D) -575.2.7 kJ
E) +575.2 kJ

Question 50

In an endothermic reaction, heat is transferred from the _____________ to the _____________.

Question 51

The standard enthalpies of formation for several substances are given below: Calculate the DH° for the reaction below.

A) -219.0 kJ
B) -69.2 kJ
C) 34.6 kJ
D) 69.2 kJ
E) 219.0 kJ

Question 52

Energy of motion is called _____________.

Question 53

The standard enthalpies of formation for several substances are given below: Determine the heat of vaporization for H₂O and C₂H₅OH.

A) 241.8 and -235.1 kJ
B) 241.8 and 325.1 kJ
C) 44.0 and 42.6 kJ
D) -54.0 and -42.6 kJ
E) -44.0 and -42.6 kJ

Question 54

In a(n) _____________ reaction, the energy of bond breaking is greater than the energy of bond making.

Question 55

Match the following:

Question 56

How much energy in kilojoules is required to vaporize a 25.0 g sample of water at 100.0°C? The heat of vaporization of water = 2260 J g^-1 at 100°C.