Question 1

Which of the following statements best describes an exothermic reaction?

Accepted Answer

It releases heat to the surroundings; $$\Delta H is $$negative.

Question 2

A reaction has $$\Delta H = -150\ \mathrm{kJ}$$ and $$\Delta S = +200\ \mathrm{J/K} at$$ $$T = 298\ \mathrm{K}. $$What is the sign of $$\Delta G$$ and is the reaction spontaneous?

Accepted Answer

$$\Delta G is $$negative; the reaction is spontaneous.

Question 3

Which of the following best describes the role of ATP in living systems?

Accepted Answer

ATP transfers energy by coupling exergonic and endergonic reactions.

Question 4

Which of the following is true about activation energy?

Accepted Answer

It is the minimum energy required for reactants to collide with proper orientation to form products.

Question 5

A nutrition label states that a snack contains 150 Calories. What does this value represent?

Accepted Answer

The energy content of the food, measured as the heat released upon combustion.

Question 6

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes speed up reactions by lowering the activation energy.

Question 7

Which of the following is a correct description of a combustion reaction?

Accepted Answer

It involves an organic molecule reacting with oxygen to produce carbon dioxide and water.

Question 8

Which of the following best describes oxidation in an inorganic redox reaction?

Accepted Answer

A metal atom loses electrons and becomes a cation.

Question 9

Which of the following is an example of an organic reduction reaction?

Accepted Answer

Conversion of an aldehyde to an alcohol.

Question 10

Which of the following statements about condensation and hydrolysis reactions is correct?

Accepted Answer

Condensation reactions produce water as two molecules join.

Question 11

Which enzyme is responsible for removing a phosphate group from a molecule in a cell?

Accepted Answer

Phosphatase

Question 12

Which of the following statements about hydrolyzable lipids is true?

Accepted Answer

They contain ester functional groups that can be broken down into carboxylic acids and alcohols.

Question 13

During the hydrogenation of an alkene, which of the following occurs?

Accepted Answer

A double bond is converted to a single bond by the addition of two hydrogen atoms.

Question 14

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of the enzyme immobilizes and orients the reactants for the reaction.

Question 15

A reaction has $$\Delta H = +50\ \mathrm{kJ}$$ and $$\Delta S = -100\ \mathrm{J/K} at$$ $$T = 300\ \mathrm{K}. $$Calculate $$\Delta G$$ and determine if the reaction is spontaneous.

Accepted Answer

$$\Delta G = +80\ \mathrm{kJ}$$; nonspontaneous

Question 16

Which of the following best describes a hydrolysis reaction?

Accepted Answer

Water is consumed and a molecule is split into two smaller molecules.

Question 17

Which of the following is true about the hydration of an alkene?

Accepted Answer

Water is added across the double bond, forming an alcohol.

Question 18

Which of the following is a feature of combustion reactions in the body?

Accepted Answer

They occur through a series of reactions, transferring energy as ATP.

Question 19

Which of the following best describes Markovnikov’s rule in the hydration of asymmetric alkenes?

Accepted Answer

The –H adds to the carbon with more hydrogen atoms, and the –OH adds to the carbon with more carbon groups attached.

Question 20

Which of the following statements about entropy ($$\Delta S) is $$correct?

Accepted Answer

A positive $$\Delta S$$ indicates an increase in randomness.

Chapter 5: Chemical Reactions – Thermodynamics, Kinetics, and Biochemical Processes

Guida di studio - Domande di pratica

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