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Instrumental Analysis > Exam Two: Electrochem > Flashcards

Exam Two: Electrochem Flashcards

1
Q

Redox reactions are what

A

electron transfer reactions

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2
Q

A redox reaction is the sum of

A

two half reactions

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3
Q

Oxidation is the

A

loss of electrons

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4
Q

Reduction is the

A

gain of electrons

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5
Q

Chemical redox reactions occur

A

in solution. Oxidant and reductant are directly mixed with one another

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6
Q

What causes redox reactions in solution

A

the direct collision of atoms, ions, etcleading to a direct transfer of electrons

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7
Q

In an electrochemical reaction

A

the two half reactions are physically separated

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8
Q

How are electrons transferred in an electrochemical cell

A
  1. through external circuit
  2. In electrodes
  3. In solution
  4. Inside salt bridge
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9
Q

What are the anolyte and the catholyte connected by

A

a salt bridge

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10
Q

oxidation occurs at the

A

anode

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11
Q

reduction occurs at the

A

cathode

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12
Q

In electrodes and external circuits, what is electron transfer based on

A

mechanism of current transfer in conductive metals

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13
Q

In the interface of electrodes and electrolytes, what is electron transfer based on

A

oxidation- reductions reactions

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14
Q

In solution, what is electron transfer based on

A

the migration of charged particles (ions)

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15
Q

anions move towards

A

anode

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16
Q

cations move towards

A

cathode

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17
Q

How are electrons transferred in the salt bridge?

A

Through moving ions

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18
Q

What is the the salt bridge composed of

A

agar saturated with KNO3 or KCl

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19
Q

Galvanic (Voltaic) cells generate electricity from a _____ redox reaction

A

spontaneous

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20
Q

Why should the anolyte and catholyte be physically separated

A

chemical reaction between the oxidizing agent and reducing agent would happen

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21
Q

Whats an example of the galvanic cell

A

Daniel cell

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22
Q

Electrolytic cells are

A

non spontaneous - external energy is needed to induce the reaction

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23
Q

example of electrolytic cell

A

electrolysis of water

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24
Q

___ is always on the left side of the salt bridge

A

The anode

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25
Q

___ is always on the right side of the salt bridge

A

The cathode

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26
Q

what is current

A

(I) is the flow of electric charge through a conductor such as a wire

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27
Q

What is the unit on current

A

A- Ampere

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28
Q

What is an ampere

A

the amount of electric charge flowing per second

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29
Q

What is charge

A

q

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30
Q

what is the unit of q

A

(C) coulomb

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31
Q

What is the electric current in an electrochemical proportional to?

A

the rate of reaction

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32
Q

Faraday’s number is the

A

charge of one mole of electrons

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33
Q

What is electric potential

A

(E) is the work needed (or that can be done) when moving an electric charge from one point to another

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34
Q

what is the unit of E

A

(V) volt

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35
Q

what is a volt

A

the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it

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36
Q

You get E with a ____ reaction

A

Spontaneous

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37
Q

You use E with a ____ reaction

A

Nonspontaneous

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38
Q

What is free energy change?

A

The maximum possible electrical work that cna be done by a reversible chemical reaction at constant temperature and pressure

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39
Q

Delta G is

A

free energy change

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40
Q

What is Ohm’s law

A

(1) Current is directly proportional to the potential difference across a circuit
(2) Current is inversely proportional to resistance of a circuit

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41
Q

What is power

A

work done per unit time

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42
Q

What is unit on power

A

J/s or watt (W)

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43
Q

Higher Current= ____ Power

A

HIgher

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44
Q

What does cell potential depend on?

A

The potential of both half cells

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45
Q

What are relative potentials of half-cells are measured against a ______

A

reference electrode

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46
Q

what is S.H.E.

A

Standard Hydrogen electrode

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47
Q

The standard reduction potential for any other half cell can be measured by

A

connecting them to S.H.E

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48
Q

When is an electrode “standard”

A

when it’s activity is 1 or it’s 1 M

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49
Q

Can the S.H.E. be the anode or the cathode?

A

Both

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50
Q

Standard half-cells reactions are written as

A

reductions

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51
Q

If Eo is positive the reaction is taking place in the

A

cathode

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52
Q

if Eo is negative the reaction is taking place in the

A

anode

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53
Q

A larger Eo indicates

A

better reduction

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54
Q

A smaller Eo indicates

A

better oxidation

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55
Q

The effect of concentration on the electrode potential is expressed by

A

Nerst Equation

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56
Q

The standard electrode potential for a half reaction can be defined as

A

electrode potential of the half-reaction when reactants and products all ave unit activity

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57
Q

Characteristics of standard electrode potential

A
  • relative potential (relative to SHE)
  • written for reduction half-reaction\
  • (+) sign when electrode acts as cathode against SHE
  • (-) sign wen electrode acts as anode against SHE
  • Depends on temperature
  • Not changed when half reaction is multiplied by any number to balance
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58
Q

What is Ecell

A

potential of complete cell

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59
Q

What is E

A

potential of complete reaction

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60
Q

What is Ec

A

potential of cathodic (reduction) half reaction

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61
Q

What is Ea

A

potential of anodic (oxidation) half reaction

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62
Q

If Ecell>0 the cell is

A

galvantic. spontaneos

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63
Q

If Ecell<0 the cell is

A

electrolytic. non-spontaneous

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64
Q

If Ea > Ec, Eo is ___, therefore the equilibrium constant, K, ____

A

negative, decreases

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65
Q

What is thermodynamic standard potential?

A

Standard potential of an electrode at ionic strength (µ) of zero

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66
Q

What is concentration standard potential?

A

By changing the ionic strength, thermodynamic standard potential is changed to concentration or apparent standard potential which has a different value.

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67
Q

What is true of gamma in concentration standard potential?

A

gamma=1 bc [] is low

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68
Q

What is conditional (formal) standard potential

A

Standard potential value dependent on activity (concentration) of a chemical species other than Red and Ox such as H+, OH-, Cl-, I-, NH3

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69
Q

What is potentiometric analysis

A

Analysis of a two-electrode system including a reference electrode and an indicator electrode

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70
Q

What is reference electrode

A

electrode with a fixed composition and constant potential

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71
Q

Three reference electrodes

A
  1. Standard hydrogen electrode (SHE)
  2. Silver-Silver Chloride Electrode (Ag/AgCl)
  3. Calomel Electrode (Hg/Hg2Cl2)
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72
Q

Whats an indicator electrode

A

The electrode with a potential related to the concentration of analyte

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73
Q

Two indicator electrodes

A
  1. metallic indicator electrodes

2. membrane indicator electrodes

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74
Q

Arbitrarily, wha is E of SHE

A

0 V

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75
Q

SHE is used in all

A

Calculations

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76
Q

SHE is not appropriate for

A

daily use

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77
Q

What does the electrode potential of the silver-silver chloride electrode depend on

A

the concentration/ activity of Cl-

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78
Q

What does the electrode potential of the calomel electrode depend on

A

the concentration/activity of Cl-

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79
Q

E of saturated calomel electrode (SCE)

A

+0.241

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80
Q

E of normal calomel electrode (NCE)

A

+0.280

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81
Q

E of desinormal calomel electrode (DCE)

A

+0.334

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82
Q

What are metallic indicators of the first kind

A

Electrodes that respond directly to changing the activity of the electrode cation

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83
Q

Two examples of metallic indicators of the first kind

A
  1. Copper Indicator: Cu l CuSO4 (xM)

2. Silver indicator: Ag l AgNO3 (xM)

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84
Q

What is need to measure cation concentration with metallic indictor electrodes of the first kind

A

reference electrode

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85
Q

Why are double junction electrodes used?

A

Assure there is no interference

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86
Q

What are metallic indicators of the second kind?

A

Electrodes that respond to changes in anion activity though formation of a complex or precipitation

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87
Q

Example of a soluble complex measured by an indicator electrode of the second kind?

A

Cu l CuY2- (aM), Y4- (x M)

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88
Q

Example of a precipitate measured by an indicator electrode of the second kind?

A

Ag l AgCl(s) l Cl- (x M)

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89
Q

What are redox electrodes

A

electrodes made of inert metals such as Pt, Au ad Pd, which are immersed in a solution of redox pairs

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90
Q

What is liquid junction potential

A

liquid junction potential develops across the boundary between two electrolyte solutions that have different compositions

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91
Q

What leads to ion diffusion is liquid junction potential

A

the separation of charge

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92
Q

What is ion mobility

A

the terminal velocity that a particle achieves in an electric field

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93
Q

What ions have the highest mobility

A

H+ and OH-

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94
Q

How can liquid junction potential be minimized?

A

placing a salt bridge between the two solutions

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95
Q

When is the salt bridge most effective in minimizing mobility?

A
  1. The mobility of the negative and positive ions in the bridge are nearly equal
  2. The concentration of the ions is large
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96
Q

What are membrane indicator electrodes?

A

Ion-selective electrodes

  • made of thin membrane capable of binding only the intended ion
  • do not involve redox process
  • called ion selective electrodes (ISE) because they respond selectively to one ion
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97
Q

Crystalline membrane electrodes

A
  1. single crystal

2. polycrystalline

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98
Q

Non crystalline membrane electrodes

A
  1. glass
  2. liquid
  3. immobilized liquid in a rigid polymer
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99
Q

Example of single crystalline membrane electrode

A

LaF3 for F-

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100
Q

Example of poly crystalline membrane electrode

A

Ags for S2- and Ag+

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101
Q

Example of glass non crystalline membrane electrode

A

silicate glasses for Na+ and H+

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102
Q

Example of liquid, noncrystalline membrane electrode

A

liquid ion exchangers for Ca2+

neutral carries for K+

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103
Q

Example of immobilized liquid in a ridged polymer, non crystalline electrode

A

PVC matrix for Ca2+ and NO3-

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104
Q

What’s a possible issue with crystalline electrodes

A

They can dissolve and need to be replaced

105
Q

What errors are associated with pH measurements

A

Alkaline error/ sodium error

Acid error

106
Q

What is alkaline/ sodium error in pH measurments

A

WHen [H+] is very low and [Na+] is high, the electrode responds to Na+ and the apparent pH is lower than the true pH.

107
Q

WHat is acid error in pH measuremnts

A

In strong acid, the measured pH is higher than the actual pH, perhaps because the glass is saturated with H+ and cannot be further protonated.

108
Q

In ion selective electrodes what is selectivity coefficient (K)

A

Gives relative response to different species with the same charge. (an electrode is intended to measure A but also responds to X where X is the interfering ion)

109
Q

The smaller the selectivity coefficient, the ____ interference there is by X

A

less

110
Q

In the general equation for potential of ion selective electrodes, when is ion charge zA, posititve

A

when the analyte is cation

111
Q

In the general equation for potential of ion selective electrodes, when is ion charge zA, negative

A

when the analyte is an anion

112
Q

What is an important consideration when designing an instrument that measures cell potential

A

The resistance may be large with respect to the cell being measured

113
Q

What will produce a significant error in an instrument measuring cell potential

A

IR drop

114
Q

What can ion selective electrodes be used in

A

Direct Potentiometry

Potentiometric Titration

115
Q

What is direct potentiometry

A

Using the Nerst equation for determining the concentration (or activity) of an analyte by measuring the potential of an indicator electrode versus a reference electrode.

116
Q

What is potentiometric titration?

A

Using potentiometry for determining the end point of titrations, inclusing acid-base, complexiometric, and redox titrations

117
Q

what methods can be used for direct potentiometry?

A

single standard calibration
multiple standard calibration
single standard addition
multiple standard addition

118
Q

How do electroanalytical techniques differ from potentiometric techniques

A

electroanalytical techniques involve current while potentiometric techniques do not

119
Q

What are the four electroanalytical techniques

A

electrogravimetry
coulometry
amperometry
voltammetry

120
Q

What are electrogravimetry, coulometry, amperometry, and voltammetry examples of

A

electrolysis

121
Q

what is electrolysis

A

the process in which a chemical reaction is forced to occur at an electrode by applying external voltage (E)

122
Q

If current is not negligible, what changes the voltage required to run the reaction

A

ohmic potential
overpotential (over voltage)
Concentration polarization

123
Q

What is Ohmic potential/ IR drop

A

The force (voltage) required to overcome the resistance of the ions to movement toward the anode an the cathode

124
Q

What law does ohmic potential follow?

A

ohm’s law

125
Q

What does the net effect of IR drop increase

A

the potential required to operate an electrolyitc cell

126
Q

What does the net effect of IR drop decrease

A

the measured potential of a galvanic cell

127
Q

What is over potential/ over voltage

A

The voltage required to overcome the activation energy for the reaction at an electrode

128
Q

What does applying potential to the metal increase

A

increases the energy of the electron in the metal

129
Q

What does applying potential tot he metal decrease

A

the activation energy for electron transfer

130
Q

What is over voltage a measure of

A

the kinetics of an electron transfer process

131
Q

For a fast system, by increasing voltage, what reaction immediately starts

A

oxidation

132
Q

For a fast system, by increasing or decreasing voltage, what begins to flow

A

current

133
Q

For a fast system, by reducing voltage what reaction immediately starts

A

reduction

134
Q

What current flows with an increase in potential

A

anodic current

135
Q

What current flows with a decrease in potential

A

cathodic current

136
Q

What is current exchange (Io)

A

the current exchanged between checmical species in solution and electrode to produce an equilibrium potential

137
Q

What does the value of current exchange, Io, depend on

A

The kinetics (rate) of the electrochemical reaction

138
Q

Is a fast system reversible or irreversible?

A

reversible

139
Q

For a slow system, is anoidic over voltage positive or negative

A

positive

140
Q

For a slow system, is cathoidic over voltage positive or negative

A

negative

141
Q

Are current exchanges for slow reactions reversible or irreversible

A

irreversible

142
Q

Why are current exchanges for slow reactions irreversible

A

a lot of energy is needed

143
Q

The less current exchange, the more or less irreversible a system is

A

more irreversible

144
Q

A totally reversible system has a very large or very small Io

A

very large Io

145
Q

A totally irreversible system has a very large pot very small Io

A

very small… almost 0

146
Q

Is the current exchange in the electrolysis of water totally reversible or totally irreversible

A

totally irreversible

147
Q

What does the magnitude of over voltage depend on

A

the desired rate of each electron transfer

the nature of of the electrode surface

148
Q

what assumption is relatively true with respect the the hardness/softness of an electrode?

A

The softer the electrode the larger n is

149
Q

What is concentration polarization

A

when the concentration of reactants or products are not the same at the surface of the electrode as they are in the bulk solution

150
Q

How mass transfer in an electrochemical cell carried out

A
  1. convection
  2. diffusion
  3. migration
151
Q

What is convection

A

From the bulk of solution to the diffusion boundary… basically the agitation of solution

152
Q

What is diffusion

A

from the diffusion boundary to the electrode due to concentration gradient

153
Q

What is migration

A

If the analyte is an ion, it can be transferred by migration under the influence of an electric field

154
Q

What is diffusion current

A

the current produced by the contribution of analytes diffused from the outer edge of the diffusion layer (nerst layer) to the surface of the electrode in the electrochemical reaction

155
Q

WHat process is diffusion

A

mass transfer process due to concentration gradient

156
Q

What can undergo diffusion

A

ions

molecules

157
Q

what is diffusion limited to

A

a thin layer of solution attached to the electrode

158
Q

what is the diffusion later/ nerst layer

A

the thin layer of solution attached to the electrode

159
Q

What can only be involved in the diffusion process

A

materials that are brought to the diffusion layer

160
Q

What does the diffusion current relate to

A

the rate of the electrochemical reaction

161
Q

What is steady-state diffusion

A

When the mass transfer by diffusion happens at a constant rate

162
Q

Under steady state diffusion what kind of current is measures

A

constant current

163
Q

What is needed to reach steady-state diffusion

A

constant convention
constant temperature
constant stirring

164
Q

If there is less convection there is less ____, and less ___

A

less molecules at the diffusion boundary (Cs)

less diffusion

165
Q

What is migration current

A

The current produced when ions that undergo electrochemical reaction from migration contribution

166
Q

The process of migration only occurs for

A

ions

167
Q

cations move towards the

A

cathode

168
Q

anions move toward the

A

anode

169
Q

What is electrolysis current (i)

A

The current at any point in the reaction determined by the rate of analyte transport from the outer edge of the diffusion layer to the electrode surface by both diffusion and migration

170
Q

If your electrode is + and your ion is +

A

diffusion occurs towards the electrode

migration occurs towards the electrode

171
Q

if your electrode is + and your ion is -

A

diffusion occurs toward the electrode

migration occurs away from the electrode

172
Q

if your electrode is - and your ion is -

A

diffusion occurs towards the electrode

migration occurs towards the electrode

173
Q

if your electrode is - and your ion is +

A

diffusion occurs towards the electrode

migration occurs towards the electrode

174
Q

in order to only have diffusion current controlling the electrolysis current the analyte partition (t) must be

A

less than 1

175
Q

what can we say if t is really small?

A

that the analyte doesn’t really contribute

176
Q

more ions means ____ analyte partition

A

less

177
Q

if migration current (im) is positive, diffusion and migration are going in _____ directions

A

the same

178
Q

if migration current (im) is positive, diffusion and migration are going in _____ directions

A

different

179
Q

how can analyte partition be minimized?

A

introducing a supporting electrolyte that have inactive ions

180
Q

At what concentration of the supporting electrolyte doe sthe total current carried by the analyte approach zero

A

when the concentration of the supporting analyte is between 50-100 fold greater than that of the analyte

181
Q

What are common supporting electrolytes

A 
KCl
KNO3
Na2SO4
LiClO4
LiNO3
HCl
H2SO4
182
Q

What is Fick’s first law of diffusion

A

Diffusion current is related to the diffusion flux which is related to the concentration gradient in the diffusion layer

183
Q

What is diffusion flux

A

the rate of flow of a substance per unit area per unit time

184
Q

Usually ____ molecules have a larger diffusion coefficient

A

smaller

185
Q

What is the nerst assumption

A

diffusion is limited to a thin layer around the electrode and we assume there is a linear concentration gradient

186
Q

When potential is applied to drive an electrolytic reaction what increases

A

current

187
Q

Once enough potential is applied what leads to the stabilization of current in electrolysis

A

diffusion

188
Q

what is the stabilization of current when increasign potential is applied in electrolysis called

A

diffusion plateau

189
Q

what does a decrease in current give?

A

cathodic wave

190
Q

what does an increase in current give

A

anodic wave

191
Q

what is limiting current

A

current at which diffusion plateau determines reaction

192
Q

How does limiting current increase

A

by increasing the concentration of the analyte in the solution

193
Q

what occurs when the concentration of the analyte is very high leading to the limiting current being very high

A

Oxidation or reduction wall

194
Q

What is an oxidation or reduction wall

A

when the diffusion plateau won’t appear in a regular scale

195
Q

What stays constant due to agitation

A

Cs

196
Q

What decreases when the solution is unstirred

A

Cs

197
Q

What kind of cell is utilized by several electroanalytical techniques

A

Three-electrode system

198
Q

What electrodes are in a three-electrode system

A

working
reference
auxiliary (counter)

199
Q

what does the working electrode do

A

makes the reaction: where to reaction of interest occurs

200
Q

What does the reference electrode do

A

has fixed potential and used to measure the potential of the working electrode

201
Q

what do we want to measure with the reference electrode

A

the potential a polarizable working electrode with significant current with respect to a nonpolarizable reference electrode with negligible current

202
Q

what is the auxiliary electrode

A

the electrode at which the opposite reaction occurs and is a current supporting partner of the working electrode

203
Q

why do you only need two electrodes in potentiometry

A

there is no current

204
Q

current cannot travel through the ___ electrode

A

reference

205
Q

What is used for controlled-potential electrolysis with three electrode cell

A

Circut

206
Q

Parts of controlled-potential electrolysis circut

A 
electrolysis cell
anode (auxiliary electrode)
cathode (working electrode)
Reference electrode
controlled potential
ammeter
potentiostat
207
Q

What is coulometry

A

measuring electrical charge ( in coulombs) ised in an electrochemical reaction

208
Q

In coulometry you measure __, to find __

A

Q to find n

209
Q

Types of coulometry

A

controlled potential coulometry (CPC)

controlled current coulometry (CCC)

210
Q

what is CPC

A

the potential of working electrode is usually adjusted on the diffusion plateau of teh analyte

211
Q

What do we assume with CPC

A

everything is absorbed at the working electrode

212
Q

What is used to determine the quantity charge required to complete an electrolysis

A

digital integrator

213
Q

in coluometry, essentially all of the ___ is consumed

A

the analyte

214
Q

What is CCC (coulometric titrations)

A

a reagent is generated on an electrode by applying constant current to react with the analyte

215
Q

What is proportional to the concentration of the analyte until the end of the titration in CCC

A

The charge consumed

216
Q

How can the end of the titration be determined in CC

A

visual (indicator) method

intrumental method

217
Q

What instrumental methods are used to determine end of CCC titration

A

amperommetry

potentiometry

218
Q

At the generator electrode what is the titrant?

A

pre-reagent

reagent

219
Q

In the solution, what is the titrant

A

analyte + reagents

products

220
Q

What does the generator electrode act like in CCC

A

burette in a titration

221
Q

What is measured instead of reagent volume in CCC

A

charge consumed at the generator electrode

222
Q

What is voltammetry

A

the realtion between current and voltage obsevred during electrochemical processes

223
Q

what is obtained in voltammetry

A

a current-potential curve (votammogram)

224
Q

What is present in voltammetry

A

significant current

225
Q

due to significant current in voltammtry, what occuRS

A

polarization

226
Q

How does voltammtry differ from coulometry

A

minimal consumption of the analyte in voltammetry

227
Q

How is the electrochemical cell set up in voltammetry

A

three electrodes immersed in solution containing analyte and an excess of supporting electrolyte

228
Q

In voltammtry, the working electrode’s potential

A

is varied linearly with time.

229
Q

why are the dimensions of the working electrode in voltammetry kept small

A

to enhance the tendency to become polarized

230
Q

What is the reference electrode commonly in voltammetry

A

SCE

Ag/AgCl

231
Q

What remains constant at the reference electrode in voltammetry

A

the potential

232
Q

What is the auxiliary electrode commonly in voltammetry

A

coil of platinum wire

233
Q

what does the platinum wire auxiliary electrode do in voltammetry

A

conducts electricity from he signal source through the solution to the working electrode

234
Q

Types of working electrodes in voltammetry

A

disk electrodes
hanging mercury drop electrode (HMDE)
microelectronic

235
Q

What is a disk working electrode?

A

disk conductors compressed into a rod of an inert material, such as teflon or kel-f, that has embedded in it a wire contact

236
Q

what can the conductors in dick electrodes be made out of?

A

noble metal (Pt, Au,…)
Carbon material (paste, pyrolytic graphite, glassy carbon, diamond, carbon nanotubes)
Semiconductor (tin, indium oxide)
metal coated with film of mercury (thin film mercury electrode)

237
Q

What is a hanging mercury drop electrode?

A

electrode consisting of a veyr fine capillary tube connected to a mercury-containing reservoir

238
Q

What forces the metal out of the capilary piston arrangement

A

micrometer screw

239
Q

what does the micrometer screw promote

A

the formation of mercury drops

240
Q

What’s the advantage of HDME

A

a fresh electrode electrode surface can be readily formed by simply producing a new drop

241
Q

What are working microelectrodes?

A

small diameter metal wires or fivers within tempered glass bodies

242
Q

What is the tip of the microelectrode polished with

A

alimunia or diamond polish

243
Q

what is the electrical connection in microelectrodes

A

0.060 inch gold plated pin

244
Q

what kinds of materials can make up microelectrodes

A

carbon fiber
platinum
gold
silver

245
Q

What is hydrodynamic voltammetry

A

voltammetry in the presence of convection (agitation)

246
Q

What can be used in hydrodynamic voltammatry

A

stationary electrode in stirred solution
rotating disk electrode
a flow through cell
dropping mercury electrode

247
Q

What is voltammetry in the absence of convection

A

using a stationary electrode in an unstirred soltuion

248
Q

What is used in voltammetry in the absence of convection

A 
line sweep voltametry (LSV)
cyclic voltammetry (CV)
pulse voltammetry
Square wave voltammetry (SWV)
249
Q

How is hydrodynamic voltammatry perfromed

A

magnetic stirrer
rotation
passing analyte solution through a tube fitted with a working electrode

250
Q

How is rotating performed in hydrodynamic voltammetry

A

the workings electrode is rotated at a constant high speed in the solution to provide stirring
(calm solution, electrode agitation)

251
Q

what is residual current

A

the current due to reaction of impurities in the solution

252
Q

in a reversible hydrodynamic voltammetric system including the reductant only what is the half wave potential equal to

A

Eo

253
Q

in an irreversible hydrodynamic voltammetric system including the reductant only what is the half wave potential NOT equal to

A

Eo

254
Q

in a reversible hydrodynamic voltammetric system including the oxidant only what is the half wave potential equal to

A

Eo

255
Q

in an irreversible hydrodynamic voltammetric system including the oxidant only what is the half wave potential NOT equal to

A

Eo

256
Q

what is polarography

A

voltammetry conducted with a dropping mercury electrode

257
Q

what electrochemical cell is used polarography

A

three-electrode cell

258
Q

What is polarograhy useful for?

A

studying reduction because H+ at the Hg surface has a large cathodic overpotential

Instrumental Analysis (2 decks)

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