Applications Of Redox In Electrochemical Analysis

Question 1

What is the Nernst equation used for

Answer 1

used in physiology for finding the electric potential of a cell membrane with respect to one type of ion

Question 2

What happens when a metal rod is dipped in a solution of its own salt

Answer 2

if the solution pressure is greater than the ionic pressure, the metal tends to dissolve forming metal ion in solution

If the ionic pressure greater than the solution pressure, ion leave the solution to be deposited on the metal rod

Question 3

Electrode potential E def

Answer 3

The potential difference between a metal rode [electrode] and the solution

Question 4

The potential difference between a metal and it’s ions is a measure of what

Answer 4

the tendency of the metal to be oxidized to metal ions or the tendency of the ion to be reduced to metal atoms

Question 5

Types of electrodes

Answer 5

Indicator
Standard or reference

Question 6

What is the indicator electrode

Answer 6

Gives the voltage or current that comes from the species in the solu on. They are sensi ve to ions concentra on.

Question 7

What is the standard or reference electrode

Answer 7

They have a fixed potential and are used to stabilize readings from indicator electrodes

Not sensitive to ion concentrations

Question 8

Types of standard electrodes

Answer 8

1) Standard hydrogen electrode
I) Saturated Calomel Electrode
III) Silver - silver Chloride electrode

Question 9

What is the standard hydrogen electrode SHE

Answer 9

It is used as reference half cell against

which all other electrodes are compared.

Question 10

What is the potential of the SHE at all temperatures

Answer 10

Zero mili volt

Question 11

Purpose of platinum in the SHE

Answer 11

takes no part in the electrochemical reaction and serves only as the sit for the transfer of electrons.

Question 12

What does the hydrogen electrode act as

Answer 12

Hydrogen electrode may act as anode or cathode depending upon the half-cell with which it is coupled.

Question 13

What are the other half cells measured relative to

Answer 13

SHE

Question 14

Disadvantages if SHE

Answer 14

• It is cumbersome and difficult to use.
• Requires purified hydrogen gas.
• Requires frequent replatization of the electrode.
• Subject to much oxidation- reduction interference and can only be used in limited cases.

Question 15

What is widely used as a secondary reference electrode

Answer 15

Saturated calomel electrode

Question 16

The components of the saturated calomel electrode SCE

Answer 16

Made of two tubes one inside the other

Inner tube has mercury, mercurous chloride (calomel)

Inner tube is connected to saturated potassium chloride solution in the outer tube through a small hole

Question 17

Calomel is what

Answer 17

Mercurous chloride

Question 18

What is the potential of SCE relative to SHE

Answer 18

244 mV

Question 19

Reaction of SHE

Answer 19

2H+ + 2e———-> H2

Question 20

Half cell reaction if SCE

Answer 20

Hg2Cl2 + 2e———> 2Hg + 2 Cl

Question 21

Components of the silver silver chloride electrode

Answer 21

silver wire, the end of which is coated with a thin layer of silver chloride. The wire is immersed in solution that contains the desired concentration of potassium chloride and that is saturated with silver.

Question 22

Potential of AgCl electrode relative to SHE

Answer 22

0.222V

Question 23

Half cell reaction of AgCl electrode

Answer 23

AgCI + e ——> Ag + CI

Question 24

How is the standard electrode potential found E0

Answer 24

By connecting the SHE with a metal electrode [ a metal in contact with a molar solution of its ions] by means of salt bridge, the standard electrode potential may be determined.

Question 25

What is the standard electrode potential

Answer 25

electromotive force produced when half-cell consisting of the element immersed in molar solution of its ions is coupled with a
SHE.