Module 5 - Coulometry and Voltammetry Flashcards
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.
Coulometry
________ is the rate of charge flow in a circuit or solution.
Current
What is the unit of current?
Ampere
_______, the electrical potential difference, is the potential energy that
results from the separation of charges.
Voltage
What is Ohm’s Law?
E = IR where E = Voltage; I = Current; R = Resistance
_________ is current that is always in one direction, that is, unidirectional.
Direct current (dc)
The direction of ________ reverses periodically.
alternating current (ac)
________ is the departure of the electrode potential from its theoretical Nernst equation value on the passage of current.
Polarization
_________ is the movement of material, such as ions, from one location to another.
Mass transfer
Reactants are transported to the surface of an electrode by three mechanisms: _______, ________, and _______. Products are removed from electrode surfaces in the same ways.
diffusion, migration, convection
___________ 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.
Diffusion
_________ is the movement of ions through a solution as a result of
electrostatic attraction between the electrodes and the ions.
Migration
__________ is the transport of ions or molecules through a solution
as a result of stirring, vibration, or temperature gradients.
Convection
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.
Voltammetry
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.
Voltammetry
What is an instrument in voltammetry that is microelectrode whose potential is varied with time?
Working electrode
An instrument electrode in voltammetry whose potential remains constant (Ag/AgCl electrode or calomel)?
Reference electrode
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.
Counter electrode
What is excess of nonreactive electrolyte (alkali metal) to conduct current in voltammetry?
Supporting electrolyte
