Module 5 - Electrochemistry

Question 1

In what type of reaction are electrons transferred from one reactant to
another?

Answer 1

Oxidation/reduction reaction

Question 2

What agent is an electron donor?

Answer 2

Reducing agent or reductant

Question 3

What agent is an electron acceptor?

Answer 3

Oxidizing agent or oxidant

Question 4

What is an arrangement in which the oxidizing agent and the reducing agent are physically separated from one another?

Answer 4

Electrochemical cell

Question 5

What isolates the reactants but maintains electrical contact between the two halves of the cell?

Answer 5

A salt bridge

Question 6

What measures the potential difference, or voltage, between the two
electrodes at any instant?

Answer 6

Voltmeter

Question 7

What happens when the cell is at equilibrium?

Answer 7

The forward reaction (left-to-right) occurs at the same rate as the reverse reaction (right-to-left), and the cell voltage is zero.

The two half reactions in a cell continue, but their rates are equal.

Question 8

What is an electrode where reduction occurs called?

Answer 8

Cathode

Question 9

What is an electrode where oxidation occurs called?

Answer 9

Anode

Question 10

What type of electrochemical cells store electrical energy?

Answer 10

Galvanic or voltaic cells

Question 11

What type of electrochemical cell consumes electricity and needs an external source of electrical energy for operation?

Answer 11

Electrolytic cell

Question 12

In a ________ cell, reversing the current reverses the cell reaction.

Answer 12

Reversible cell

Question 13

In an _________ cell, reversing the current causes a different half-reaction to occur at one or both of the electrodes.

Answer 13

Irreversible cell

Question 14

What are the charge carriers within the electrochemical cell?

Answer 14

Anions and cations

Question 15

The _____________ of a substance is a reference state that allows us to obtain
relative values of such thermodynamic quantities as free energy, activity, enthalpy,
and entropy.

Answer 15

Standard state

Question 16

If the reactants and products are in their standard states, the resulting cell potential
is called the _________________.

Answer 16

standard cell potential

Question 17

This rule implies that we always measure the cell potential
by connecting the positive lead of the voltmeter to the right-hand electrode in the schematic or cell drawing (reduction side, gains electrons) and the common, or ground, lead of the voltmeter to the left-hand electrode.

Answer 17

Plus right rule

Question 18

When we consider a normal chemical reaction, we speak of the reaction occurring
from reactants on the ______ side of the arrow to products on the _____ side.

Answer 18

Left; right

Question 19

The __________________ has been used throughout the world for many years as a universal reference electrode.

Answer 19

Standard hydrogen electrode (SHE)

Question 20

The standard hydrogen electrode is sometimes called the __________.

Answer 20

Normal hydrogen electrode (NHE)

Question 21

The potential of the hydrogen electrode is assigned a value of exactly ________ at all temperatures.

Answer 21

0.000 V

Question 22

An _______________ is the potential of a cell that has a standard hydrogen electrode as the left electrode (reference).

Answer 22

electrode potential

Question 23

An electrode potential is by definition a ___________. An oxidation
potential is the potential for the half-reaction written in the opposite
way. The sign of an oxidation potential is, therefore, opposite that for a
_________, but the magnitude is the same.

Answer 23

reduction potential

Question 24

The ______________ for a half-reaction, E0, is defined as the electrode potential when all reactants and products of a half-reaction are at unit activity. Note that the quotient is always equal to 1 when the activities of the reactants and products of a half-reaction are unity.

Answer 24

standard electrode potential

Question 25

True or false: when redox systems are at equilibrium, the electrode potentials of all redox couples that are present are identical.

Answer 25

True

Question 26

What does a positive standard cell potential (E0) imply?

Answer 26

The reaction is spontaneous