Exploring Chemical Analysis: Electrode potentials Flashcards

loss of electrons

gain of electrons

electrons are transferred from one species to another. A molecule is said to be oxidized when it loses electrons. It is reduced when it gains electrons.

also called an oxidant, takes electrons from another substance and becomes reduced.

also called a reductant, gives electrons to another substance and is oxidized in the process. In the reaction

Electric charge (q)

F=96 485.3321 s A / mol

(I) is the quantity of charge flowing each second past a point in an electric circuit.

• which is a flow of one coulomb per second.
• The unit of current

a device to conduct electrons into or out of the chemicals involved in the redox reaction.

a molecule that can donate or accept electrons at an electrode.

is a chemical reaction in which we apply a voltage to drive a redox reaction that is not spontaneous (not energetically favorable) and would not otherwise occur.

• The difference between two points measures the work that can be done (or is needed) when electrons move from one point to another.
• The greater the potential difference between points A and B, the more work can be done (or must be done) when electrons travel from point A to point B. Potential difference is measured in volts (V).

it is energetically favorable for reactants to be converted into products. Energy released from the chemicals could be available as electrical energy.

• a spontaneous chemical reaction generates electricity.
• an electrochemical cell that produces a potential difference by the conversion of chemical energy into electrical energy

is a junction that connects the anodic and cathodic compartments in a cell or electrolytic solution.

electrode at which reduction occurs

the electrode at which oxidation occurs

• measures the tendency for a given chemical species to be reduced.
• The standard oxidation potential measures the tendency for a given chemical species to be oxidized as opposed to be reduced.

• an electrode that scientists use for reference on all half-cell potential reactions.
• The value of the standard electrode potential is zero, which forms the basis one needs to calculate cell potentials using different electrodes or different concentrations.

The potential for a cell containing a specified concentration of reagent other than 1 M

• responds to analyte concentration
• potential changes in order to measure things

• maintains a fixed (reference) potential
• self contained

• an electrode where the metal (silver) is in contact with a slightly soluble salt (silver chloride), which in turn is in contact with a solution containing the common anion (chloride ion).
• The ions in the solid phase and those in the liquid phase are in equilibrium. ​ ​

a reference electrode based on the reaction between elemental mercury and mercury (I) chloride.

*when saturated Cl- does not change with evaporating liquid.

the SI unit of electromotive force, the difference of potential that would drive one ampere of current against one ohm resistance.

if you do not want the analyte and electrode to have direct contact.

• Metal electrodes
• ion selective electrodes(I.S.E..)

Electromotive force of a cell

standard reduction potential

molar gas constant

temperature in degrees Kelvin

number of moles of electrons transferred

Faraday’s constant (96,500 C/mol)

the reaction quotient (a function of the activities or concentrations of the chemical species involved)

a substance that dissociates into ions in solution and acquires the capacity to conduct electrons

• The reduction potential for a redox couple measured with
  respect to a standard hydrogen electrode set at zero.
• The electromotive force of an electrochemical cell.

• liquids: 1M concentration,
• gases: pressure 1 bar
• Temperature; 298 K(25°C )

o Calculate the voltage of an electrochemical cell
o Find the concentration of one of the components in a system

an electrochemical cell in which chemical reactions occur through the application of an external potential difference