Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Instrumental > Electroanalytical Chemistry > Flashcards

Electroanalytical Chemistry Flashcards

1
Q

What are some advantages of electroanalytical chemistry?

A

It provides information about sample activity rather than concentration
It is cheap and can be miniaturized
It is specific for a particular oxidation state of an element

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Who is Michael Faraday?

A

The creator of the law of electrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Who is Walter Nernst?

A

The creator of the Nernst equation
E = Eo — ((RT/zF))lnQ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Who is Jaroslav Heyrovsky?

A

The inventor of polarography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the main branches of electroanalytical chemistry?

A

Potentiometry
Coulometry
Voltammetry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is potentiometry?

A

The measure of the potential of electrochemical cells without drawing substantial current
EX — pH measurements, ion-selective electrodes, titrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is coulometry?

A

The measure of the electricity required to drive an electrolytic redox reaction to completion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is voltammetry>?

A

The measurement of current as a function of applied potential under conditions that keep a working electrode polarized

EX — cyclic voltammetry, biosensors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a galvanic cell?

A

A cell that produces electrical energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an electrolytic cell?

A

A cell that consumes electrical energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a chemically-reversible cell?

A

A cell in which reversing the direction of the current reverses the reactions at the two electrodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do electrons do during conduction?

A

Electrons serve as carriers
EX — moving from Zn through the conductor to Cu

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does electricity involve in conduction?

A

Electricity involves the movement of anions and cations in solutions
EX — in salt bridges, both Cl- and K+ move

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What occurs at the electrode surface during conduction?

A

Oxidation or reduction occurs depending on which electrode is being examined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Reduction occurs in which electrode?

A

Cathode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Oxidation occurs at which electrode?

A

Anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is oxidation?

A

The loss of an electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is reduction?

A

The gaining of an electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are Faradaic currents?

A

The direct transfer of electrons
EX — oxidation at one electrode and reduction at the other

20
Q

What are non-Faradaic currents?

A

The increasing of a charge on its double layer (no idea what that means but ok)

21
Q

What is electrical charge (q) measured by?

A

Coulombs (C)

22
Q

What is electrical current (I) measured in?

A

Amperes (A)

23
Q

What is Ohm’s law?

A

E=IR
Potential = (electrical current)(resistance)

24
Q

What is potential (E) measured in?

A

Volts (V)

25
Q

What is resistance (R) measured in?

A

Ohms

26
Q

What can the reactions in electrochemical cells be thought of as?

A

Two half-cell reaction, each with its own characteristic electrode potential
These measure the driving force for the reaction
Always written as reductions

27
Q

What is standard electrode potential (Eo)?

A

The measure of individual potentials of an electrode at standard conditions

28
Q

What is the standard hydrogen electrode?

A

A universal reference, but it is only hypothetical and not used in practice
Uses a platinum electrode that oxidizes 2H+ to H2 (g)
Very sensitive to temperature, pressure, and H+ activity

29
Q

What is used instead of the SHE?

A

The standard calomel electrode (SCE) is used since SHE is difficult to make

30
Q

What is one of the most common potentiometric measurements?

A

pH measurements

31
Q

What does the common glass pH electrode use?

A

It makes use of junction potentials to determine the hydronic ion concentration in a sample solution

32
Q

What reference electrode is used for glass pH electrodes?

A

Ag/AgCl electrodes

33
Q

What connects the reference electrode to the sample solutions in glass pH electrodes?

A

A small frit or hole

34
Q

What is a combination pH electrode?

A

It combines the indicator and the reference into a single unit

35
Q

What is the potential of this cell? (Not really pointing out a single cell but its what it said in the PP)

A

Ecell = Eref1 + Eij + Eoj + Eref2
Eij/Eoj are junction potentials at the inner/outer layers of the glass membrane

36
Q

What is a junction potential?

A

It occurs at the interface of two electrolytes, caused by unequal diffusion rates of cation and anions across the boundary (small hole in a salt bridge)

37
Q

Why is the surface of the glass pH electrode hydrated?

A

It being hydrated allows for the exchange of hyrdronium ions for the cation in the glass (Na or Li)

38
Q

what are the four interface regions of pH electrodes?

A
  1. The external solution and hydrated glass
  2. The hydrated glass and dry glass on the outside
  3. The dry glass and hydrated glass on the inside
  4. The hydrated glass and the internal solution
39
Q

Are the two hydrated glass/dry glass interfaces identical?

A

If the glass is uniform, the interfaces should be identical and have the same junction potential

40
Q

What is the junction potential when taking glass interface junction potentials into consideration?

A

Because the interface junction potentials are identical, they cancel each other out.
So, that means the junction potential is the difference between the internal and external solutions

41
Q

How do errors in pH measurements with glass electrodes arise?

A

Calibration problems
Junction potential
High [Na+] interacting with electrode
High acid concentration
Equilibration time
Temperature control

42
Q

What are the accuracy and precision performances for typical electrodes?

A

Accuracy = +/- 0.02 pH units
Precision = +/- 0.02 pH units

43
Q

What is the ion selective electrode (ISE)?

A

An ISE generally consists of the ion-selective membrane, an internal reference electrode, an external reference electrode, and a voltameter

EX — an ISE for F-

44
Q

What is conductometry?

A

The detection of electrical conductivity

45
Q

What are some applications for conductometry?

A

Condictometric detection in ion-exchange chromatography (IEC/IC)
Capillary electrophoresis (CE)

46
Q

What is conductometry used for?

A

To detect titration endpoints

Instrumental (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions