Module 5 - Coulometry and Voltammetry

Question 1

What method is based on electrolysis carried out long enough to ensure complete oxidation or reduction of the analyte to a product of known composition? In this method, the amount of analyte is determined by measuring the quantity of electrical charge needed for complete conversion to a product.

Answer 1

Coulometry

Question 2

________ is the rate of charge flow in a circuit or solution.

Answer 2

Current

Question 3

What is the unit of current?

Answer 3

Ampere

Question 4

_______, the electrical potential difference, is the potential energy that
results from the separation of charges.

Answer 4

Voltage

Question 5

What is Ohm’s Law?

Answer 5

E = IR where E = Voltage; I = Current; R = Resistance

Question 6

_________ is current that is always in one direction, that is, unidirectional.

Answer 6

Direct current (dc)

Question 7

The direction of ________ reverses periodically.

Answer 7

alternating current (ac)

Question 8

________ is the departure of the electrode potential from its theoretical Nernst equation value on the passage of current.

Answer 8

Polarization

Question 9

_________ is the movement of material, such as ions, from one location to another.

Answer 9

Mass transfer

Question 10

Reactants are transported to the surface of an electrode by three mechanisms: _______, ________, and _______. Products are removed from electrode surfaces in the same ways.

Answer 10

diffusion, migration, convection

Question 11

___________ is the movement of a species under the influence of a concentration gradient. It is the process that causes ions or molecules to move from a more concentrated part of a solution to a more dilute.

Answer 11

Diffusion

Question 12

_________ is the movement of ions through a solution as a result of
electrostatic attraction between the electrodes and the ions.

Answer 12

Migration

Question 13

__________ is the transport of ions or molecules through a solution
as a result of stirring, vibration, or temperature gradients.

Answer 13

Convection

Question 14

What is an electrochemical method in which information about an analyte is obtained by measuring current (I) as a function of applied potential? Only a small amount of sample (analyte) is used.

Answer 14

Voltammetry

Question 14

What is an electrochemical method in which information about an analyte is obtained by measuring current (I) as a function of applied potential? Only a small amount of sample (analyte) is used.

Answer 14

Voltammetry

Question 15

What is an instrument in voltammetry that is microelectrode whose potential is varied with time?

Answer 15

Working electrode

Question 16

An instrument electrode in voltammetry whose potential remains constant (Ag/AgCl electrode or calomel)?

Answer 16

Reference electrode

Question 17

An instrument in voltammetry that uses Hg or Pt that completes the circuit, conducts e- from signal source through the solution to the working electrode.

Answer 17

Counter electrode

Question 18

What is excess of nonreactive electrolyte (alkali metal) to conduct current in voltammetry?

Answer 18

Supporting electrolyte