Deck 5: Energy Changes in Chemical Reactions

Question 1

The work done by a person while moving a 15.0 kg sphere at an acceleration of 2.0 m/s² to a store at a distance of 6.0 meters from its original position is _____J.

A) 1.8 × 10²
B) 0.9 × 10²
C) 1.8 × 10¹
D) 18 × 10²
E) 2.5 × 10²

Answer 1

1.8 × 10²

Question 2

The energy contained in batteries is an example of chemical energy.

Answer 2

True

Question 3

The negative sign associated with the pressure-volume work done indicates that the system gains energy.

Answer 3

False

Question 4

The force exerted by gravity on a 25 lb object lifted to a height of 6.0ft above the ground is _____ N. ( Given work done = 2.0 × 10² J)

A) 1.1 × 10²
B) 1.8 × 10²
C) 11 × 10²
D) 2.0 × 10²
E) 2.4 × 10²

Question 5

What is the SI unit of energy?

A) Fahrenheit
B) Joules
C) Newton
D) Pascal
E) Ohm

Question 6

The energy that results from atomic or molecular motion is called _____.

A) radiant energy
B) chemical energy
C) nuclear energy
D) thermal energy
E) electrical energy

Question 7

Nuclear energy is a form of a potential energy.

Question 8

The _____ of an object is a measure of its thermal energy content.

Question 9

The energy that is stored in an object because of its relative positions or orientations of its components is called _____.

Question 10

A closed system can exchange energy but not matter with its surroundings.

Question 11

What are the factors that influence the amount of work done while moving an object?

Question 12

Electrical energy is the energy carried by light, microwaves, and radio waves.

Question 13

The kinetic energy of a bicycle that weighs 23.5 kg moving at a speed of 25.0 miles per hour is _____ J.

A) 5.87 × 10³
B) 2.93 × 10³
C) 2.68 × 10³
D) 0.29 × 10³
E) 1.47 × 10³

Question 14

Which of the following can be categorized as potential energy?

A) The energy released during a landslide
B) The energy associated with a bullet in a gun
C) The energy associated with a moving bicycle
D) The energy associated with a swinging pendulum
E) The energy released when kicking a ball

Question 15

If the enthalpy of a reaction is negative, then the enthalpy of the products is greater than the enthalpy of the reactants.

Question 16

Which of the following is an example of radiant energy?

A) Energy contained in lightning
B) Energy stored in petrol
C) Energy obtained from sunlight
D) Energy contained in boiling water
E) Energy emitted from radioactive materials

Question 17

_____ is the thermal energy that can be transferred from an object at one temperature to an object at another temperature.

Question 18

Explain with an example, how potential energy is transformed into kinetic energy.

Question 19

The potential energy associated with a person weighing 78 kg standing at the edge of a diving board 4.0 ft above the water level is _____ .

A) 3.0 × 10²
B) 5.9 × 10³
C) 9.3 × 10³
D) 9.3 × 10²
E) 5.9 × 10²

Question 20

Different forms of energy are expressed in different units.

Question 21

If ΔT and q values are positive, then the heat flows from the surroundings into an object.

Question 22

The magnitude of thermal change of an object depends only on the amount of thermal energy transferred.

Question 23

Bomb calorimeter is a constant-pressure calorimeter.

Question 24

The standard enthalpy of formation of any element in its most stable state is zero.

Question 25

_____ is an example of a state function.

A) Pressure-volume work
B) Mechanical work
C) Heat
D) Pressure
E) Distance

Question 26

A(n) _____ is a property of a system whose magnitude depends only on the present state of the system, not its previous history.

Question 27

The amount of heat absorbed or released by the calorimeter is equal in magnitude and opposite in sign to the amount of heat produced or consumed by the reaction.

Question 28

The enthalpy change for a reaction depends on the path by which the reactants are converted to products.

Question 29

A(n) _____ system exchanges neither energy nor matter with the surroundings.

Question 30

The balanced chemical equation corresponding to the standard enthalpy of formation of NaCl is:

A) Na₂(s) + Cl₂(g) → 2NaCl(s).
B) 2Na(s) + Cl₂(g) → 2NaCl(s).
C) Na(s) + Cl₂ (g)→ NaCl(s).
D) Na(s) + ½ Cl₂(g)→ NaCl(s).
E) Na(s) + Cl(g)→ NaCl(s).

Question 31

In the equation ΔE = q + w, the symbol E represents the _____.

A) heat
B) temperature
C) enthalpy
D) internal energy
E) work done

Question 32

The small well-defined part of a universe in which we are interested is referred to as a(n) _____.

Question 33

In an exothermic process:

A) the volume of the system decreases at constant pressure.
B) the heat is transferred to the system from its surroundings.
C) the value of q is less than zero by convention.
D) the enthalpy of products is greater than the enthalpy of the reactants.
E) the enthalpy of the reaction is positive.

Question 34

Define standard enthalpies of formation.

Question 35

The _____ of a system is a complete description of the system at a given time, including its temperature and pressure, the amount of matter it contains, its chemical composition, and the physical state of the matter.

A) internal energy
B) state
C) enthalpy
D) work
E) entropy

Question 36

The enthalpy change that occurs when a reaction is carried out with all reactants and products in their standard state is known as the _____.

Question 37

The units of specific heat (C_s) are J/(mol.0°C)

Question 38

A process in which heat is transferred from a system to its surroundings is described as _____.

Question 39

Consider the equation CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O (l). The ΔH^o_comb of methane is _____ kJ/mol.
(Given ΔH^o_f values of methane, carbon dioxide, and water is -74.6, -393.5, and -285.8 kJ/mol respectively)

A) -890.5
B) -799.8
C) -1033
D) 890.5
E) 799.8

Question 40

State Hess's law. How can it be used to calculate the enthalpy change of a reaction that cannot be observed directly?

Question 41

The amount of heat absorbed by 500.0 kg sodium chloride used in a thermal energy storage unit, when the temperature of the salt increases from 15.0 ^oC to 38.0^oC is _____. (Given, C_s of NaCl = 0.864 J/g.^oC)

A) 9.94 × 10³ kJ
B) 9.94 × 10⁶ kJ
C) 1.64 × 10³ kJ
D) 1.64 × 10⁴ kJ
E) 8.63 × 10⁶ kJ

Question 42

Which of the following has the highest heat capacity?

A) Methanol
B) Benzene
C) Graphite
D) Liquid water
E) Water vapour

Question 43

The reported caloric content of foods does not include the ΔH_comb of _____.

A) carbohydrates
B) vitamins
C) proteins
D) fats
E) minerals

Question 44

Define heat capacity. What are the factors that determine the heat capacity of an object?

Question 45

Human body usually exhausts the supply of stored carbohydrates before utilizing the fat reserves.

Question 46

Fiber contributes to the caloric content of food in humans.

Question 47

Which of the following is an essential amino acid?

A) Glycine
B) Threonine
C) Alanine
D) Serine
E) Aspartic acid

Question 48

Which of the following devices is best suited to measure the enthalpy changes that accompany combustion reactions?

A) Coffee-cup calorimeter
B) Constant-pressure calorimeter
C) Bomb calorimeter
D) Heat balance calorimeter
E) Constant flux calorimeter

Question 49

The number of calories expended by a 60.0 kg person bicycling at 15.0 miles per hour is _____ kcal.

A) 3.22 × 10^-1
B) 2.32 × 10^-1
C) 6.44 × 10^-1
D) 4.46 × 10^-1
E) 5.46 × 10^-1

Question 50

How are the enthalpy changes that accompany combustion reactions measured using a bomb calorimeter?

Question 51

_____ is the amount of energy needed to raise the temperature of an object exactly by 1°C.

Question 52

The caloric content of a meal that contains 81.5 g of water, 76.8 g of protein, 25.8 g of fat, 12.0 g of carbohydrates, and 2.0 g of minerals is approximately _____ Cal.

A) 842
B) 587
C) 971
D) 1030
E) 902

Question 53

A device used to measure enthalpy changes in chemical processes at constant pressure is _____.

Question 54

A glass of milk contains 85.0 g of water, 5.0 g of carbohydrates, 3.0 g of fats, and 5.0 g of proteins. The caloric content of milk is _____ Cal.

A) 92
B) 77
C) 67
D) 52
E) 65

Question 55

The nitrogen in foods, when burned in a calorimeter is transformed into urea.

Question 56

In the equation q = mC_sΔT, C_s represents _____.

A) heat capacity
B) specific heat
C) change in enthalpy
D) state function
E) molar heat capacity

Question 57

The structure given below is the structure of _____.

A) alanine
B) glycine
C) valine
D) lysine
E) serine

Question 58

The enthalpy of combustion is negative for all the substances that can be burned.

Question 59

_____ describes a set of techniques employed to measure enthalpy changes in chemical processes using calorimeters.

Question 60

The _____ is the amount of energy needed to increase the temperature of 1 mol of a substance by 1°C.

A) specific heat
B) molar heat capacity
C) enthalpy
D) state function
E) change in enthalpy

Question 61

The amount of energy released during the combustion of 0.018 gal of ethanol that has a density of 0.78 g/mL is _____ kJ. (Given ΔH^o_comb of ethanol = -1371 kJ/mol).

A) -2.0 × 10³
B) -3.0 × 10³
C) -4.5 × 10³
D) -0.5 × 10³
E) -1.6 × 10³

Question 62

What is syngas?

Question 63

_____ is a unit used to indicate the caloric content of food.

Question 64

Anthracite has high sulfur content because of the presence of small particles of pyrite.

Question 65

How are the caloric values reported for foods different from the enthalpy of combustion of the same foods burned in a calorimeter?

Question 66

Coal contains large number of _____ atoms in their structure that link parts of the structure together, in addition to the basic framework of carbon-carbon bonds.

A) hydrogen
B) sulfur
C) oxygen
D) helium
E) nitrogen

Question 67

What are the different approaches that can be used to determine the caloric content of foods?

Question 68

_____ is the partially decayed remains of plants that grow in swampy areas and gives off little heat when burnt.

A) Anthracite
B) Graphite
C) Peat
D) Lignite
E) Bituminous coal

Question 69

The amino acids that a human body is unable to synthesize from the other compounds are called _____.

Question 70

_____ is a type of coal that has the lowest oxygen content and the highest ΔH_comb.

A) Bituminous
B) Subbituminous
C) Steam coal
D) Lignite
E) Anthracite

Question 71

Which of the following types of coal has high oxygen content and the lowest ΔH_comb?

A) Anthracite
B) Lignite
C) Subbituminous
D) Bituminous
E) Graphite

Question 72

The hydrogen:carbon mole ratio in lignite is _____.

A) 0.5
B) 0.6
C) 0.8
D) 1.0
E) 0.9

Question 73

How is coal converted to liquid fuels?

Question 74

Consider the equation C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O. The ΔH^o_comb for the given reaction is _____.
(Given ΔH^o_f values of C₂H₅OH = -277.60 kJ/mol, CO₂ = -393.50 kJ/mol, and H₂O = -285.30 kJ/mol)

A) -1920.5 kJ
B) 1365.3 kJ
C) -1365.3 kJ
D) -1642.9 kJ
E) 1920.5 kJ

Question 75

In the human body, the nitrogen from foods is converted to _____ before excretion.

Question 76

Primary sources of energy like natural gas are more efficient when used directly than in the form of a secondary source such as electricity.

Question 77

The structure of coal is more similar to an aliphatic hydrocarbon structure than an aromatic hydrocarbon.

Question 78

The energy required by a 55 kg person to climb a 1-story building (Assume each flight of stairs is 18 ft high.) is _____ kcal.

A) 2.56
B) 0.0256
C) 0.700
D) 3.51
E) 9.71

Question 79

Coal liquefaction techniques are economically less attractive than the production of liquid fuels from petroleum.

Question 80

The amount of energy released by the combustion of 2 moles of benzene is _____kJ. (ΔH^o_comb of benzene = -41.8 kJ/g)

A) -3.34 × 10³
B) -8.36 × 10³
C) -6.52 × 10³
D) -5.60 × 10³
E) -7.21 × 10³