Analytical Chem Wpr 2

Front 1

Amperometry

Back 1

measurement of electric current for analytical purposes.

Front 2

auxiliary electrode

Back 2

current-carrying partner of the working electrode in electrolysis

Front 3

charging current

Back 3

electric current arising from charging or discharging of the electric double layer at the electrode-solution interface.

Front 4

concentration polarization

Back 4

occurs when an electrode reaction occurs so rapidly that the concentration of the solute near the surface of the electrode is not the same as the concentration in bulk solution.

Front 5

controlled potential electrolysis

Back 5

technique for selective reduction (or oxidation), in which the voltage between the working and reference electrodes is held
constant.

Front 6

Coulometry

Back 6

technique in which the quantity of analyte is determined by measuring the number of coulombs needed for complete electrolysis

Front 7

counter electrode

Back 7

current-carrying partner of the working electrode. Also called auxiliary electrode.

Front 8

cyclic voltammetry

Back 8

polarographic technique with a triangular waveform. Both cathodic and anodic currents are observed for reversible reactions

Front 9

diffusion current

Back 9

in polarography, the current observed when the rate of reaction is limited by the rate of diffusion of analyte to the electrode. Diffusion current = limiting current – residual current.

Front 10

electrogravimetric analysis

Back 10

technique in which the mass of an electrolytic deposit is used to quantify the analyte.

Front 11

Electrolysis

Back 11

process in which the passage of electric current causes a chemical reaction to occur.

Front 12

Faradiac current

Back 12

component of current in an electrochemical cell due to oxidation and reduction reactions.

Front 13

Overpotential

Back 13

potential above that expected from equilibrium potential, concentration polarization, and ohmic potential needed to carry out an electrolytic reaction at a given rate. It is 0 for a reversible reaction.

Front 14

ohmic potential

Back 14

voltage required to overcome the electric resistance of an electrochemical cell.

Front 15

Polarizable

Back 15

one whose potential can change readily when a small current flows.

Front 16

Voltammetry

Back 16

analytical method in which the relation between current and voltage is observed during an electrochemical reaction

Front 17

Hydrolysis

Back 17

“reaction with water.”

Front 18

Formal concentration

Back 18

molarity of a substance if it did not change its chemical form on being dissolved. Represents the total number of substance dissolved in a liter of solution, regardless of any reactions that take place when the solute is dissolved.

Front 19

Buffer

Back 19

mixture of an acid and its conjugate base. A buffered solution is one that resists changes in pH when acids or bases are added.

Front 20

Polyprotic systems

Back 20

compound that can donate or accept more than one proton.

Front 21

Zwitterion

Back 21

molecule with a positive charge located at one position and a negative charge localized at another position.

Front 22

Amphiprotic

Back 22

one that can act as both a proton donor and a proton acceptor. The intermediate species of polyprotic acids are amphiprotic.

Front 23

end point

Back 23

point in titration at which there is a sudden change in physical property, such as indicator color, pH, conductivity, or absorbance. Used as a measure of the equivalence point.

Front 24

equivalence point

Back 24

point in titration at which the quantity of titrant is exactly sufficient for stoichiometric reaction with the analyte.

Front 25

leveling effect

Back 25

the strongest acid that can exist in solution is the protonated form of the solvent. A stronger acid will donate its proton to the solvent and leveled to the acid strength of the protonated solvent. Similarly, the strongest base that can exist in a solvent is the deprotonated form of the solvent

Front 26

speciation

Back 26

describes the distribution of an element or compound among different chemical forms.

Front 27

titration curve

Back 27

a graph showing how the concentration of a reactant or a physical property of the solution varies as one reactant (the titrant) is added to another (the analyte).

Front 28

transition range

Back 28

for an acid-base indicator, the pH range over which the color change occurs. For a redox indicator, the potential range over which the color change occurs.

Front 29

Ammeter

Back 29

measures electric current in a circuit.

Front 30

Capacitor

Back 30

consists of a pair of conductors separated by a dielectric (insulator). When voltage exists across conductors, an electric field is present in the dielectric. The field stores energy and produces a mechanical force between the conductors.

Front 31

Capacitance

Back 31

ability of a body to hold an electrical charge

Front 32

Current

Back 32

flow of electric charge or the rate of flow of an electric charge

Front 33

Ideal voltage source

Back 33

circuit element where the voltage across it is independent of the current through it.

Front 34

Impedance

Back 34

describes a measure of opposition to alternating current. Defined as the frequency domain ratio of the voltage to the current. AKA voltage-current ratio for a single complex exponential at a particular frequency

Front 35

Load

Back 35

if an electric circuit has a well-defined output terminal, the circuit connected to this terminal (input impedence) is the load.

Front 36

Voltmeter

Back 36

instrument used for measured the electrical potential difference between two points in an electric circuit.

Front 37

Voltage source

Back 37

any device/system that produces an electromotive force between its terminals OR derives a secondary voltage from a primary source of the electromotive force.

Front 38

Resistance

Back 38

measure of the degree to which an object opposes an electric current through it.

Front 39

Resistor

Back 39

two-terminal electrical component that produces voltages across its terminals that is proportional to the electric current passing through it in accordance w/ Ohm’s law: V=IR

Front 40

Transducer

Back 40

devices that converts one type of energy to another.

Front 41

Series circuits

Back 41

circuits that are next to each other.

Front 42

Parallel circuits

Back 42

circuits that are on opposite paths.

Front 43

redox indicator

Back 43

compound used to find the end point of a redox titration because its various oxidation states have different colors. The standard potential of the indicator must be such that its color changes near the equivalence point of the titration.

Front 44

Preoxidation

Back 44

in some redox titrations, adjustment of the analyte oxidation state to a higher value so that it can be titrated with a reducing agent.

Front 45

Prereduction

Back 45

process of reducing an analyte to a lower oxidation state prior to performing a titration with an oxidizing agent.

Front 46

Fraction of dissociation, α

Back 46

for the disassociation of an acid (HA), the fraction of acid in the form A-

Front 47

Fraction of association, α

Back 47

for the reaction of a base (B) with H2O, the fraction of base in the form BH+

Front 48

Buffer capacity, Beta

Back 48

a measure of the ability of a buffer to resist changes in pH. The larger the buffer capacity, the greater the resistance to pH change.