Deck 6: Chemical Reactions: Energy, Rates, and Equilibrium

Question 1

Which of the following is a potential consequence of misjudging the caloric needs of a patient?

A) malnourishment
B) muscle fatigue
C) respiratory failure
D) coma
E) All of the above are consequences.

Answer 1

All of the above are consequences.

Question 2

The energy difference between I and III in the diagram is called

A) the activation energy
B) kinetic energy
C) heat of reaction
D) exothermic energy
E) endothermic energy

Answer 2

heat of reaction

Question 3

How would this diagram be different if the reaction was exothermic?

A) III would be lower than I
B) No difference; this reaction is already exothermic.
C) II would be lower than III.
D) II would be lower, between I and III.
E) II would be lower than I.

Answer 3

III would be lower than I

Question 4

How is a biochemical pathway different than a biochemical reaction?

A) Actually, they are identical.
B) Only pathways occur in cells not reactions.
C) Only reactions occur in cells not pathways.
D) Reactions are catabolic, and pathways are anabolic.
E) A pathway is a specific sequence of reactions.

Question 5

The following reaction is a reversible reaction.Which statement BEST describes what it means for this reaction to be reversible? HCOOH + HOCH₃ ⇌ HCOOCH₃ + H₂O

A) This reaction only occurs in the reverse direction as written above.
B) All of the reactant molecules react to make product, and then all of the product molecules react to make reactants again.
C) Forward and reverse reactions proceed at the same rate.
D) Forward and reverse reactions occur simultaneously.
E) The rate of the reverse reaction is must faster than the rate of the forward reaction.

Question 6

A calorimeter is used to measure the energy content of foods because the energy measurement obtained using a calorimeter is the same as the energy we obtain by eating.Which of the following statements explains why this is the case?

A) They are the same because both the calorimeter and body combust food to obtain only heat energy.
B) They are the same because both the calorimeter and body combust food in a single exothermic step.
C) They are the same because both the calorimeter and body combust food in a complex series of steps.
D) They are the same because, overall, metabolism is a combustion reaction.
E) Actually, they are not the same values.

Question 7

Combustion reactions are ___________ because products of the reaction are _________ in potential energy than the reactants.

A) endothermic; higher
B) exothermic; higher
C) endothermic; lower
D) exothermic; lower
E) endothermic; the same

Question 8

During anabolism, heat is absorbed.What does the absorption of heat tell us about how these reactions occur?

A) These reactions do not usually occur because they require energy.
B) These reactions occur very quickly.
C) These reactions occur very slowly.
D) These reactions are driven by heat-releasing chemical reactions.
E) These reactions are not required by the body.

Question 9

Which of the following statements BEST describes catabolic pathways? I.Catabolic pathways build larger molecules from smaller ones.
II)Overall, catabolic pathways release energy.
III)An example of catabolism is when starch is broken down into smaller units of glucose during digestion.

A) I only
B) II only
C) III only
D) I and II
E) II and III

Question 10

Each of the following figures represents a reaction.Which reaction(s)has/have the slowest rate?

A) a and b
B) a, b, c, d and e
C) all but d
D) b only
E) b and e

Question 11

Which of the following changes increases the rate of a reaction?

A) adding a catalyst
B) decreasing temperature
C) decreasing concentration
D) removing product as it is formed
E) All of the above increase the rate of a reaction.

Question 12

How is the joule related to the calorie?

A) 1 cal = 4.184 J
B) 1 J = 4.184 cal
C) 1 Calorie = 4.184 J
D) 1 J = 4.184 Calorie
E) 1 J = 4.184 kcal

Question 13

By moving, breathing, and living, you do work every day.Work requires energy.Where does this energy come from?

A) The energy comes from food; it undergoes chemical reactions in the cells.
B) The energy does not come from anyplace; it is always in our bodies.
C) The energy comes from breaking bonds in food.
D) The energy comes from breaking bonds in food, oxygen, and water.
E) No one really understands where this energy comes from.

Question 14

One serving of animal crackers (30 g)contains 4.5 g of fat, 22 g of carbohydrates, and 2 g of proteins.Which of the following equations would you use to determine the number of calories in one serving of animal crackers?

A) 4.5 g × 4 Cal/g + 22 g × 9 Cal/g + 2 g × 4 Cal/g
B) 4.5 g × 9 Cal/g + 22 g × 4 Cal/g + 2 g × 4 Cal/g
C) 4.5 g × 4 Cal/g + 22 g × 4 Cal/g + 2 g × 4 Cal/g
D) 4.5 g × 9 Cal/g + 22 g × 9 Cal/g + 2 g × 4 Cal/g
E) 4.5 g × 4 Cal/g + 22 g × 4 Cal/g + 2 g × 9 Cal/g

Question 15

An endothermic reaction is one that

A) releases heat.
B) has no heat of reaction.
C) absorbs heat.
D) has reactants higher in energy than products.
E) has a negative heat of reaction.

Question 16

If a reaction has a ΔH_rxn > 0, the reaction is

A) impossible.
B) exothermic.
C) endothermic.
D) explosive.
E) important in metabolism.

Question 17

A reaction occurs between the large black spheres and the small grey spheres.Each of the boxes below represents different reaction conditions for that reaction.Which box contains the reaction conditions that leads to the fastest reaction?

A) diagram a
B) diagram b
C) diagram c
D) diagram d
E) diagram e

Question 18

The sum of bond energies of bonds broken minus the sum of bond energies of bonds formed is the definition of

A) nutritional energy.
B) heat of reaction.
C) endothermic.
D) exothermic.
E) energy diagram.

Question 19

Identify the false statement regarding bond energy.

A) Bonds with higher bond energies are stronger.
B) Stronger bonds have lower potential energy.
C) A single bond is stronger than a double bond.
D) A triple bond is stronger than a double bond.
E) Compounds with weaker bonds are more reactive.

Question 20

Combustion reactions are ___________ because products of the reaction are _________ in potential energy than the reactants.

A) endothermic; higher
B) exothermic; higher
C) endothermic; lower
D) exothermic; lower
E) endothermic; the same

Question 21

An overview of metabolism is shown in the following figure.What does this figure tell us about the energy of catabolism and anabolism?

A) Anabolic reactions occur more quickly than catabolic reactions.
B) Catabolism is exothermic, and anabolism is endothermic.
C) Overall, we exert more energy than we consume.
D) Overall, the amount of energy that goes into anabolic processes is the same as is released in catabolic processes.
E) The conservation of energy does not apply to biological systems.

Question 22

What is a biochemical pathway?

A) the path that nutrients take through the body when they are metabolized
B) the complex blood transport system
C) a chemical reaction in the body that releases energy
D) a chemical reaction that releases carbon dioxide
E) a particular sequence of chemical reactions in the body

Question 23

What type of human calorimetry is the most practical, and why?

A) direct calorimetry because it is the most accurate
B) indirect calorimetry because it is the most accurate
C) direct calorimetry because it is portable and less expensive
D) indirect calorimetry because it is portable and less expensive
E) direct and indirect calorimetry are equally practical

Question 24

What are biological catalysts called?

A) proteins
B) nucleic acids
C) enzymes
D) carbohydrates
E) lipids

Question 25

The reaction of water with ammonia is shown below.What will happen if ammonium is added to the solution when it is at equilibrium? NH₃ + H₂O ⇌ NH₄⁺ + OH^-
ammonia water ammonium hydroxide

A) Nothing will happen.
B) The result is not predictable.
C) The ammonium will bubble.
D) The equilibrium will shift to the right.
E) The equilibrium will shift to the left.

Question 26

The ΔH for the reaction described by the energy diagram below is

A) very large.
B) greater than zero but not necessarily very large.
C) exactly zero.
D) less than zero.
E) It is not possible to predict anything about the ΔH of this equation.

Question 27

A spirometer is used in indirect calorimetry.What does a spirometer measure?

A) oxygen
B) carbon dioxide
C) exhaled water
D) body heat
E) food intake

Question 28

An endothermic reaction absorbs heat when it occurs.How can the equilibrium of an endothermic reaction be shifted toward the products?

A) It is not possible to do this.
B) Add more products.
C) Cool down the reaction.
D) Add a catalyst.
E) Heat the reaction.

Question 29

During anabolism, heat is absorbed.What does the absorption of heat tell us about the relative energies of the starting small molecules and products of anabolism?

A) The products are lower energy than the reactants.
B) The reactants and products must be the same energy.
C) There is no consistent relationship between heat and the relative energies of the small molecules.
D) The reactants are lower energy than the products.
E) Actually, heat is not absorbed during anabolism.

Question 30

The first law of thermodynamics states that

A) atoms are neither created nor destroyed during a chemical reaction.
B) energy is created when reactions release energy.
C) energy is conserved.
D) atoms are destroyed to produce energy from a chemical reaction.
E) kinetic energy is conserved but potential energy is not.

Question 31

Which of the following processes are anabolic?

A) muscle building as a result of steroid use
B) releasing energy from food during the citric acid cycle
C) weight loss as a result of burning fat
D) transferring bond energy from food to ATP
E) All of the above are anabolic processes.

Question 32

Which of the following statements describes an endothermic chemical reaction?

A) During photosynthesis, plants harvest light energy in order to drive the synthesis of carbohydrates from CO₂ and H₂O.
B) A natural gas burner can be used to heat water.
C) Melting an ice cube requires temperatures above freezing.
D) Metabolizing food supplies the body with the energy required to heat ourselves and move.
E) Exposing water to cold temperatures results in freezing.

Question 33

Which of the following reactions could be described by the energy diagram below?

A) 2 CO₂ + 556 kJ→ 2 CO + O₂
B) CH₄ + 2 O₂ → CO₂ + 2 H₂O + heat
C) 8 H₂S + heat → 8 H₂ + S₈
D) 6 CO₂ + 6 H₂O + heat → C₆H₁₂O₆ + 6 O₂
E) All of the reactions can be described by this energy diagram.

Question 34

During catabolism of food, heat is released.Where does this energy go?

A) It is turned into heat energy.
B) It is used in movement.
C) It is used to drive additional chemical reactions.
D) It is transferred to ATP.
E) All of the above are possible.

Question 35

The chemical reaction in the diagram below is a(n)_____________ reaction.

A) activated
B) kinetic
C) heated
D) exothermic
E) endothermic

Question 36

Which of the following molecules is a special energy carrier molecule?

A) DNA
B) adenosine triphosphate
C) citric acid
D) insulin
E) starch

Question 37

Which of the following diagrams illustrates an endothermic reaction?

A) I and III
B) II and III
C) I and II
D) I only
E) II only

Question 38

Which part of the following energy diagram is changed when a catalyst is added, and how is it changed?

A) I is higher.
B) II is higher.
C) III is higher.
D) I is lower.
E) II is lower.

Question 39

Which of the following biological molecules are the major nutrients that make up the food that we eat? I. Proteins
II.Nucleic acids
III.Steroids
IV.Fats
V.Carbohydrates

A) All of these are major nutrients.
B) I, II, IV, and V
C) I and V
D) III, IV, and V
E) I, IV, and V

Question 40

Which of the following statements describe how oxygen intake relates to caloric requirements? I.Oxygen reacts with food to produce energy.
II)The larger the oxygen intake, the higher the energy output.
III)Oxygen is a product of food metabolism.

A) All of these statements describe the relationship between oxygen intake and caloric requirements.
B) I and II describe the relationship between oxygen intake and caloric requirements.
C) II and III describe the relationship between oxygen intake and caloric requirements.
D) I and III describe the relationship between oxygen intake and caloric requirements.
E) Only II describes the relationship between oxygen intake and caloric requirements.

Question 41

Which statement describes reaction rate?

A) Reaction rate is how fast a reaction proceeds.
B) Reaction rate is measured by the disappearance of reactants over time.
C) Reaction rate is measured by the appearance of products formed over time.
D) Reaction rate is determined, in part, by activation energy.
E) All of the above statements describe reaction rate.

Question 42

Metabolism is

A) the breakdown of food.
B) the citric acid cycle.
C) the process by which fat is stored or burned.
D) all catabolic and anabolic pathways in the body.
E) the tendency to gain or lose weight.

Question 43

Which of the following reactions releases the smallest amount of heat?

A) diagram a
B) diagram b
C) diagram c
D) diagram d
E) diagram e

Question 44

Carbohydrates and fats are sources of energy for cells because

A) they contain many C-C and C-H bonds, which are high in potential energy.
B) they are easy to metabolize.
C) they are readily absorbed from food.
D) they contain many C-C and C-H bonds, which are low in potential energy.
E) Both a and c are correct.

Question 45

In order for a reaction to occur, reactant molecules must attain a certain amount of energy called _______.

A) ΔH
B) energy
C) entropy
D) activation energy
E) Any of the above.

Question 46

A hot dog contains 151 Calories.How many joules of energy is this?

A) 36 joules
B) 632 joules
C) 632,000 joules
D) 3.6 × 10⁴ joules
E) 360 joules

Question 47

The reaction, shown below, that occurs in a hydrogen fuel cell is exothermic.According to the conservation of energy, the reverse reaction (the electrolysis of water) 2 H₂ + O₂ → 2 H₂O hydrogen fuel cell
2 H₂O → 2 H₂ + O₂ electrolysis of water

A) is also exothermic.
B) is endothermic.
C) does not involve energy.
D) has an energy change of zero.
E) involves energy in some way, but it is impossible to determine how.

Question 48

The nutritional unit of energy is the

A) calorie.
B) Calorie or kcal.
C) joule.
D) thermal unit.
E) heat of reaction.

Question 49

Which statement best describes the relationship between the heat of reaction and reaction rate?

A) There is no readily predictable relationship between ΔH and reaction rate.
B) Exothermic reactions are always slow.
C) Endothermic reactions are always slow.
D) The heat of reaction is always larger than reaction rate.
E) The relationship depends on whether the reaction is endothermic or exothermic.

Question 50

Which of the following reactions releases the most heat?

A) diagram a
B) diagram b
C) diagram c
D) diagram d
E) diagram e

Question 51

Increasing the concentration of the reactants causes the:

A) reactants to move faster.
B) reactants to collide more frequently.
C) reactants to collide with more energy.
D) rate of reaction to decrease.
E) All of the above result from increasing the concentration.

Question 52

Compounds that are used as fuels

A) contain C-C bonds.
B) contain C-H bonds.
C) are high in potential energy.
D) contain weak bonds.
E) All of these are used as fuels.

Question 53

One serving (45 g)of dry wild rice contains 1.5 g of fat, 35 g of carbohydrates, and 5 g of protein.How many Calories does a serving of wild rice contain?

A) 166 Calories
B) 170 Calories
C) 200 Calories
D) 340 Calories
E) 370 Calories

Question 54

Each of the following figures represents a reaction.Which reaction has the fastest rate?

A) diagram a
B) diagram b
C) diagram c
D) diagram d
E) diagram e

Question 55

Why does increasing the concentration of reactants typically increase the rate of a reaction?

A) A higher concentration of reactants means a higher kinetic energy per molecule.
B) A higher concentration of reactants means a lower activation energy.
C) A higher concentration of reactants means that a catalyst has been added.
D) A higher concentration of reactants means a higher activation energy.
E) A higher concentration of reactants means more collisions per amount of time.

Question 56

Which of the following reactions absorbs heat?

A) diagram a
B) diagram b
C) diagram c
D) diagram d
E) diagram e

Question 57

The name for the heat energy released or absorbed in a chemical reaction is

A) energy.
B) endothermic.
C) exothermic.
D) heat of reaction.
E) entropy.

Question 58

When bonds break, energy is

A) always released.
B) always absorbed.
C) typically released but sometimes absorbed.
D) typically absorbed but sometimes released.
E) absorbed half the time and released half the time.

Question 59

How does increasing the temperature of a reaction affect the reaction rate?

A) It slows the rate down by changing the heat of reaction.
B) It speeds the rate up by raising the activation energy.
C) It slows the rate down by increasing the activation energy.
D) It speeds the rate up by increasing the kinetic energy of the molecules.
E) It slows the rate down by increasing the kinetic energy of the molecules.

Question 60

How many nutritional Calories are in a food sample containing 550 kcal?

A) 5,500,000
B) 550,000
C) 5,500
D) 550
E) 55

Question 61

Select the TRUE statement concerning rate of reactions.

A) A large activation energy indicates high heat of reaction.
B) A small activation energy indicates high heat of reaction.
C) A large activation energy indicates low heat of reaction.
D) A small activation energy indicates low heat of reaction.
E) The activation energy is independent of the heat of reaction.

Question 62

Which statement BEST describes how calorimetry is used in medicine?

A) Calorimetry is used to feed patients.
B) Calorimetry is used to measure the temperature of a patient.
C) Calorimetry is used to measure the oxygen needs of a patient.
D) Calorimetry is used to assess the caloric needs of a patient.
E) All of the above describe calorimetry use in medicine.

Question 63

Which process that occurs during this reaction gives off heat? 2 H₂ + O₂ → 2 H₂O

A) breaking H-H
B) breaking O-O
C) breaking O-H
D) forming O-H
E) both breaking and forming bonds

Question 64

Select the correct statement regarding the reactants and products in the reaction represented by the energy diagram below.

A) The products have more energy than the reactants.
B) The reactants are more stable than the products.
C) The products are more stable than the reactants.
D) The reactants and products have the same energy.
E) The products are less stable than the reactants.

Question 65

Which of the following diagrams illustrates an exothermic reaction?

A) I and III
B) II and III
C) I and II
D) I only
E) II only

Question 66

Atwater and Rosa built the first human calorimeter in the 1890s.After measuring the energy expenditure and food and oxygen intake of humans, they made a key discovery about the transformation of matter and energy in the human body.What discovery did they make?

A) Amazingly, humans exert more energy than they take in.
B) Humans are inefficient and don't exert as much energy as they take in.
C) They confirmed that the conservation of energy applies to humans.
D) Direct calorimetry is the gold standard for accurate measurement.
E) All of the above were discovered.

Question 67

Which statement BEST describes how the temperature of the surroundings changes as a result of the reaction represented by energy diagram below?

A) The temperature of the surroundings does not change.
B) The temperature of the surroundings increases.
C) The temperature of the surroundings decreases.
D) The surroundings will become very cold.
E) It is not possible to predict anything about the temperature of the surroundings based on this diagram.

Question 68

Select the TRUE statement concerning rate of reactions.

A) A large activation energy indicates a fast reaction.
B) A catalyst increases the activation energy.
C) Low temperatures help reactants to collide with each other.
D) Slow reactions have high activation energies.
E) All of the above statements are true.

Question 69

Bond breaking is always endothermic and yet catabolism, the breakdown of nutrients, is an overall exothermic process.How can you reconcile these two statements?

A) Catabolism is an exception to the rule.
B) Bond breaking is not really always endothermic.
C) Endothermic bond breaking is only seen in the laboratory.
D) No one really understands this.
E) Catabolism is the sum of many reactions, including many bond-making reactions.

Question 70

The reaction between acetic acid (CH₃COOH)and methanol (CH₃OH)is given below, followed by a list of changes that could be made to the reaction.Which of these changes will result in the equilibrium shifting to the left? CH₃COOH + CH₃OH ⇌ CH₃COOCH₃ + H₂O
Changes that could be made to the solution
I.Adding more CH₃COOH
II.Removing H₂O
III.Adding more CH₃COOCH₃
IV.Removing CH₃OH

A) All of these changes will result in the equilibrium shifting to the left.
B) Only I will result in the equilibrium shifting to the left.
C) Only IV will result in the equilibrium shifting to the left.
D) I and III will result in the equilibrium shifting to the left.
E) III and IV will result in the equilibrium shifting to the left.

Question 71

Increasing the temperature of an exothermic reaction at equilibrium results in

A) a shift to the right.
B) a shift to the left.
C) products being produced more quickly.
D) reactants being used up more quickly.
E) Both c and d are correct.

Question 72

Which statement is the BEST definition of chemical equilibrium?

A) the point at which the mass of reaction products equals the mass of the reactants
B) the point at which forward and reverse reactions proceed at the same rate
C) the point at which a reaction is balanced
D) the point at which the number of moles of product equals the number of moles of reactants
E) Both answers b and d correctly define equilibrium.

Question 73

Select the TRUE statement concerning a reaction at equilibrium.

A) The forward reaction continues to convert reactants into products.
B) The reverse reaction continues to convert products into reactants.
C) The rate of the forward reaction is the same as the rate of the reverse reaction.
D) The concentration of each reactant and product is constant.
E) All of the above are true concerning a reaction at equilibrium.

Question 74

The energy difference between I and II in the diagram is called

A) the activation energy
B) kinetic energy
C) heat of reaction
D) exothermic energy
E) endothermic energy

Question 75

How is the reaction that occurs in a calorimeter different from human metabolism?

A) One is a combustion reaction, and the other is not.
B) One occurs in many steps, and the other does not.
C) One is exothermic, and the other is endothermic.
D) One releases carbon dioxide, and the other does not.
E) These reactions are exactly the same.

Question 76

Which bonds are broken, and which bonds are formed during this chemical reaction? 2 H₂ + O₂ → 2 H₂O

A) Broken: H-H and O-O Formed: O-H
B) Broken: H-H Formed: O-H and O-O
C) Broken: O-O Formed: O-H and H-H
D) Broken: O-H Formed: O-O and H-H
E) Broken: O-H Formed: O-H

Question 77

How many joules of energy are contained in 350 cal?

A) 350 J
B) 1,500 J
C) 1,466.2 J
D) 84 J
E) 83.65 J

Question 78

Increasing the temperature of a reaction causes the

A) reactants to move faster.
B) reactants to collide more frequently.
C) reactants to collide with more energy.
D) rate of reaction to increase.
E) All of the above result from increasing the temperature.

Question 79

Convert 3.5 × 10⁴ J to calories.

A) 8,365 calories
B) 0.84 calories
C) 8.4 × 10³ calories
D) 1.5 × 10⁵ calories
E) 14,644 calories

Question 80

An exothermic reaction is one that:

A) has a positive ΔH.
B) has no ΔH.
C) absorbs heat.
D) has products higher in energy than reactants.
E) has a negative ΔH.