Deck 12: Chemical Reactions, Oxidation, and Reduction: Bringing Molecules to Life

Question 1

Which of the following species behave as nucleophiles? Select all that apply.

A) Cl^-
B) H⁺
C) OH
D) CH₂CH₂
E) NO₂⁺

Answer 1

A,C,D

Question 2

Which of the following species behave as electrophiles? Select all that apply.

A) CN^-
B) CH₃CH₂⁺
C) H⁺
D) H₂O
E) CHCH

Answer 2

B,C

Question 3

The stoichiometry of a reaction tells us which of the following?

A) The rate at which a reaction occurs.
B) The amount of energy liberated during the course of a reaction.
C) The number of steps from which an overall reaction, from reactants to products, is formed.
D) The amount of energy required to initiate a reaction.
E) The relative quantities of reactants and products associated with a particular reaction.

Answer 3

E

Question 4

Which of the following statements about chemical reactions are true? Select all that apply.

A) Chemical reactions involve the breaking of bonds between atoms in molecules, and the formation of new bonds between different groups of atoms.
B) During chemical reactions, valence electrons always move as pairs.
C) The reactants associated with a particular reaction react in different relative quantities depending on the temperature at which the reaction is being performed.
D) Chemical reactions always result in full valence shells being maintained.
E) Chemical reactions require the movement of valence electrons.

Question 5

Which of the following statements about valence electrons are false? Select all that apply.

A) When heterolytic cleavage occurs, a pair of valence electrons is distributed unequally between two atoms.
B) We use a curly arrow to denote the movement of a pair of valence electrons.
C) The movement of valence electrons during a chemical reaction is random.
D) During a chemical reaction, valence electrons can move both within and between molecules.
E) The movement of valence electrons during a chemical reaction is described by the reaction scheme.

Question 6

Which of the following statements are true? Select all that apply.

A) An electrophile must possess a partially empty orbital.
B) A nucleophile must be able to donate a pair of valence electrons.
C) A non-bonding pair is not a suitable valence pair for a nucleophile to donate.
D) When a nucleophile donates a pair of valence electrons to an electrophile, an ionic bond is formed.
E) A double bond can act as a nucleophile.

Question 7

The cleavage of the H-Br bond is most likely to generate which of the following pairs of species?

A) H⁺ and Br^-
B) H^- and Br⁺
C) H^ and Br^

Question 8

Which of the following bonds are most likely to break homolytically? Select any that apply.

A) H-Br
B) Cl-Cl
C) C-H
D) C-C
E) O-H

Question 9

Electromagnetic radiation in which of the following regions of the electromagnetic spectrum is most able to generate free radicals?

A) Radio wave
B) Cosmic wave
C) Infrared
D) Visible
E) Ultraviolet

Question 10

The following reaction represents which stage in a free-radical reaction?

A) Initiation
B) Propagation
C) Termination

Question 11

Which of the following statements regarding free radicals are true? Select all that apply.

A) Antioxidants catalyse free radical reactions by encouraging the formation of free radicals.
B) A chain reaction involves a sequence of linked propagation reactions.
C) Free-radical reactions involve heterolytic bond cleavage.
D) Free radicals can only be generated from molecules possessing non-polar bonds.
E) The initiation of a free-radical reaction by ultraviolet light is called photolysis.

Question 12

When we forcibly increase the proportion of free radicals entering the termination step of a free-radical reaction we are said to be doing what?

A) Extinguishing the reaction
B) Terminating the reaction
C) Quenching the reaction
D) Exhausting the reaction
E) Expunging the reaction

Question 13

Match the correct terms with the following descriptions.
-A loss of electrons during the course of a reaction

A) Oxidation
B) Reduction

Question 14

Match the correct terms with the following descriptions.
-A gain of electrons during the course of a reaction

A) Oxidation
B) Reduction

Question 15

During the process NADH → NAD⁺ the electron carrier NAD is being reduced.

Question 16

Based on the following standard reduction potentials, which of the following species acts as the strongest oxidizing agent?
Zn²⁺(aq) + 2e^- ⇌ Zn(s)_; E° = -0.34v
Cl2(g) + 2e^- ⇌ 2Cl-(aq); E° = 1.36v
Ca²⁺(aq) + 2e^- ⇌ Ca(s); E° = -2.87v
2H⁺(aq) + 2e^- ⇌ H2(g); E° = 0.00v

A) Zn²⁺(aq)
B) Cl₂(g)
C) Ca²⁺(aq)
D) 2H⁺(aq)

Question 17

The reference electrode against which other standard reduction potentials are measured is which of the following?

A) The platinum electrode
B) The iron electrode
C) The copper electrode
D) The zinc electrode
E) The hydrogen electrode

Question 18

During the course of a reaction, the oxidation number of oxygen increases from -2 to 0. Is oxygen being oxidized or reduced during this reaction?

A) Oxidized
B) Reduced