ANACHEM 11 12

Question 1

relationship between chemical reaction
and electricity (movement of electrons

Answer 1

ELECTROCHEMISTRY

Question 2

it is the measurement of current/voltage
generated by the activity of an ion

Answer 2

ELECTROCHEMISTRY

Question 3

Electrochemistry Analysis

Answer 3

• redox titration
• potentiometry - widely used
• amperometry
• polarography
• electrogravimetry
• voltammetry

Question 4

• A pair of
  electrodes in contact with an electrolyte
  solution

Answer 4

Electrochemical Cell

Question 5

An
electrochemical cell which
spontaneously produces current (or
energy) when the electrodes are
connected externally by a
conducting wire.

Answer 5

. Galvanic or Voltaic Cell -

Question 6

An electrochemical cell through
which current is forced by a battery
or some other external source of
energy. (such as battery, DC,
alternate current)

Answer 6

Electrolysis or Electrolytic Cell

Question 7

The
algebraic sum of the individual electrode
potentials of an electrochemical cell at
zero current

Answer 7

Theoretical Cell Potential -

Question 8

• the amount of
  potential that is lost on the way from the
  reference electrode to the working
  electrodes.

Answer 8

Ohmic Drop, IR

Question 9

A potential
developed across a boundary between
electrolytes differing in concentration or
chemical composition

Answer 9

Liquid-junction Potential

Question 10

one way of measuring how
easily the substance loses on
electron.

Answer 10

Standard Electrode Potential

Question 11

Electrode potential
measured in solutions where all
reactants and products are at
unit activity.

Answer 11

Standard Electrode Potential

Question 12

The potential
of an electrode measured relative to a
standard, usually the SHE. It is a
measure of the driving force of the
electrode reaction and is temperature
and activity dependent

Answer 12

Electrode Potential E

Question 13

This consists of a platinum electrode
coated with platinum black to catalyze
the electrode reaction and over the
surface of which hydrogen at 760 mm of
mercury is passed.

Answer 13

Standard Hydrogen Electrode

Question 14

One in which the halfcell reactions are reversed by reversing
the current flow; such a cell is said to be
in thermodynamic equilibrium

Answer 14

REVERSIBLE CELL

Question 15

The electrode at which
reduction occurs

Answer 15

CATHODE

Question 16

The electrode at which
oxidation occurs.

Answer 16

ANODE

Question 17

occur together but opposite
direction.

Answer 17

Half-cell Reactions

Question 17

The additional
potential required to cause some
electrode reactions to proceed at an
appreciable rate

Answer 17

Activation Overpotential

Question 18

Oxidation or reduction reaction
occurring at an electrode

Answer 18

Half-cell Reactions

Question 19

In an oxidation/reduction reaction
electrons are transferred from one
reactant to another. (occurs together)

Answer 19

REDOX REACTIONS

Question 20

consists of two conductors called
electrodes, each of which is
immersed in an electrolyte solution.

Answer 20

Electrochemical Cells

Question 20

• the
  additional voltage that is needed to carry
  out electrolysis in addition to the
  standard cell potential.

Answer 20

Concentration Overpotential

Question 21

In most of the cells that will be of
interest to us, the solutions
surrounding the two electrodes are
different and must be separated to
avoid direct reaction between the
reactants

Answer 21

Electrochemical Cells

Question 22

consume
electricity. In contrast to a voltaic cell,
requires an external source of
electrical energy for operation.

Answer 22

electrolytic cells

Question 22

store electrical energy.

Answer 22

Galvanic cells

Question 23

: In redox methods an indicator electrode is used to sense the presence or change in concentration of the oxidized and reduced forms of a redox couple.

Answer 23

INDICATOR ELECTRODE

Question 24

an electrode that has a stable and well known electrode potential.

Answer 24

REFERENCE ELECTRODE

Question 25

The electrode consists of two concentric glass tubes, the inner one of which contains mercury in contact with a paste of mercury, mercury (1) chloride (calomel), and potassium chloride.

Answer 25

Calomel Electrode

Question 26

This consists of a silver wire, coated with silver chloride and in contact with a solution of potassium chloride saturated with silver chloride

Answer 26

Silver-silver Chloride Electrode

Question 26

Used to find the concentration of solute in a solution

Answer 26

Potentiometry

Question 27

Potential is measured under the conditions of no current flow

Answer 27

Potentiometry

Question 28

based on measuring the potential of electrochemical cells without drawing appreciable current.

Answer 28

Potentiometry

Question 29

- w sample dilution;

Answer 29

INDIRECT ISE

Question 29

an electrochemical transducer capable of responding to one given ion. they are selective and sensitive method; but not specific

Answer 29

ion-selective electrodes.

Question 30

- w/o sample dilution;

Answer 30

DIRECT ISE

Question 31

a potential that varies in the concentration of analyte

Answer 31

Indicator Electrode

Question 32

Potentiometry USES

Answer 32

pH and pCO₂ tests

Question 33

an accurately known electrode potential

Answer 33

Reference Electrode

Question 34

ideal reference electrode has a potential that is accurately known. constant, and completely insensitive to the composition of the analyte solution

Answer 34

Reference Electrode

Question 34

half-cell having a known electrode potential that remains constant at constant temperature and is independent of the composition of the analyte solutioN

Answer 34

Reference Electrode

Question 35

Reference Electrode Some common examples

Answer 35

a. Saturated calomel electrode b. Silver/silver hydrogen electrode c. Standard hydrogen electrode d. pH electrode

Question 35

has a potential that varies in a known way with variations in the concentration of an analyte.

Answer 35

INDICATOR ELECTRODE

Question 35

ideal indicator electrode responds rapidly and reproducibly to changes in the concentration of an analyte ion

Answer 35

INDICATOR ELECTRODE

Question 36

INDICATOR ELECTRODE TYPES

Answer 36

1. metallic, 2. membrane, and 3. ion-sensitive field effect transistors

Question 37

One potential advantage of an ion-selective electrode is the ability to incorporate it into a flow cell for the continuous monitoring of wastewater streams.

Answer 37

➢ Environmental Chemistry

Question 37

ion-selective electrodes are important sensors for clinical samples because of their selectivity for analytes in complex matrices

Answer 37

Clinical Chemistry.

Question 38

Use a pH electrode to monitor the change in pH during the titration for determining the equivalence point of an acid-base titration.

Answer 38

Potentiometric Titrations.

Question 39

the known pH of a reference solution is determined by using two electrodes, a glass electrode and a reference electrode, and measuring the voltage (difference in potential) generated between the two electrodes

Answer 39

glass-electrode method,

Question 39

thin membrane is called the

Answer 39

Electrode membrane.

Question 40

liquid inside the glass electrode usually has a pH o

Answer 40

7

Question 40

immersed in a solution of unknown pH

Answer 40

glass electrode (indicator) and SCE (reference)

Question 41

This other electrode, paired with the glass electrode, is called the

Answer 41

reference electrode

Question 42

measurements provide a rapid and convenient method for determining the activity of a variety of cations and anions

Answer 42

Direct Potentiometry

Question 42

e technique requires only a comparison of the potential developed in a cell containing the indicator electrode in the analyte solution with its potential when immersed in one or more standard solutions of known analyte concentration

Answer 42

Direct Potentiometry

Question 43

serve as the internal reference for the glass electrode.

Answer 43

n indicator glass electrode and a silver/silver chloride reference —

Question 44

measurements are also readily adapted to applications requiring req continuous and automatic recording of analytical data

Answer 44

Direct Potentiometry

Question 44

endorsed by the National Institute of Standards and Technology (NIST), similar organizations is based upon potentiometric determination of pH of unknown solution followed after calibration of the meter with standard buffers

Answer 44

operational definition of pH

Question 45

remarkably versatile tool for the measurement of pH under many conditions

Answer 45

glass/calomel electrode system

Question 45

Values registered by the glass electrode tend to be somewhat high when the pH is less than about 0.5

Answer 45

The Acid Error

Question 46

ordinary glass electrode tends to be somewhat sensitive to alkali metal ions and gives low readings at pH values greater than 9.

Answer 46

the Alkaline Error.( sodium error)

Question 47

operational definition of pH is endorsed

Answer 47

National Institute of Standards and Technology (NIST) and the IUPAC

Question 48

may cause erratic electrode performance.

Answer 48

Dehydration

Question 49

has been found that significant errors may occur when the pH of samples of low ionic strength, such as lake or stream water, is measured with a glass/calomel electrode system

Answer 49

Errors in Low Ionic Strength Solutions.

Question 50

A fundamental source of uncertainty for which a correction cannot be applied is the junction-potential variation resulting from differences in the composition of the standard and the unknown solution

Answer 50

Variation In Junction Potential

Question 51

provide data that are more reliable than data from titrations that use chemical indicators and are particularly useful with colored or turbid solutions and for detecting the presence of unsuspected species.

Answer 51

Potentiometric Titrations

Question 51

inaccuracies in the preparation of the buffer used for calibration or any changes in its composition during storage cause an error in subsequent pH measurements

Answer 51

Error in the pH Of The Standard Buffer

Question 52

offer additional advantages over direct potentiometry. Because the measurement is based in the titrant volume that causes a rapid change in potential near the equivalence point,

Answer 52

Potentiometric titrations