Module 5 - Electrochemistry Flashcards
(26 cards)
In what type of reaction are electrons transferred from one reactant to
another?
Oxidation/reduction reaction
What agent is an electron donor?
Reducing agent or reductant
What agent is an electron acceptor?
Oxidizing agent or oxidant
What is an arrangement in which the oxidizing agent and the reducing agent are physically separated from one another?
Electrochemical cell
What isolates the reactants but maintains electrical contact between the two halves of the cell?
A salt bridge
What measures the potential difference, or voltage, between the two
electrodes at any instant?
Voltmeter
What happens when the cell is at equilibrium?
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.
What is an electrode where reduction occurs called?
Cathode
What is an electrode where oxidation occurs called?
Anode
What type of electrochemical cells store electrical energy?
Galvanic or voltaic cells
What type of electrochemical cell consumes electricity and needs an external source of electrical energy for operation?
Electrolytic cell
In a ________ cell, reversing the current reverses the cell reaction.
Reversible cell
In an _________ cell, reversing the current causes a different half-reaction to occur at one or both of the electrodes.
Irreversible cell
What are the charge carriers within the electrochemical cell?
Anions and cations
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.
Standard state
If the reactants and products are in their standard states, the resulting cell potential
is called the _________________.
standard cell potential
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.
Plus right rule
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.
Left; right
The __________________ has been used throughout the world for many years as a universal reference electrode.
Standard hydrogen electrode (SHE)
The standard hydrogen electrode is sometimes called the __________.
Normal hydrogen electrode (NHE)
The potential of the hydrogen electrode is assigned a value of exactly ________ at all temperatures.
0.000 V
An _______________ is the potential of a cell that has a standard hydrogen electrode as the left electrode (reference).
electrode potential
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.
reduction potential
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.
standard electrode potential
