Chapter 13 Flashcards
anode
Electrode at which oxidation occurs. In electrophoresis, it is the positively charged electrode.
cathode
Electrode at which reduction occurs. In electrophoresis, it is the negatively charged electrode.
coulomb
C, Amount of charge per second that flows past any point in a circuit when teh current is 1 ampere.
current
I, amount of charge flowing through a circuit per unit time (A/s).
electric potential
E, The electric potential (in volts) at a point is the energy (in joules) needed to bring one coulomb of positive charge from infinity to that point. The potential difference between two points is the energy needed to transport one coulomb of positive charge from the negative point to the positive point .
electrochemistry
Use of electrical measurements on a chemical system for analytical purposes. Also refers to use of electricity to drive a chemical reaction or use of a chemical reaction to produce electricity.
electrode
An electrical conductor through which electrons flow into or out of chemical species involved in a redox reaction.
Faraday constant
The number of coulombs in a mole of elementary charges
formal potential
Potential of a half-reaction (relative to a standard hydrogen electrode) when the formal concentrations of reactants and products are unity. Any other conditions (such as pH, ionic strength, and concentrations of ligands) also must be specified.
galvanic cell
One that produces electricity by means of a spontaneous chemical reaction. Also called a voltaic cell.
half-reaction
Any redox reaction can be conceptually broken into two half-reactions, one involving only oxidation and one involving only reduction.
joule
SI unit of energy.
Latimer diagram
One that shows the reduction potentials connecting a series of species containing an element in different oxidation states.
Nernst equation
Relates the voltage of a cell, E, to the activities of reactants and products.
ohm
SI unit of electrical resistance.
Ohm’s law
States that the current, I, in a circuit is proportional to voltage, E, and inversely proportional to resistance, R.
oxidant
Oxidizing agent
oxidation
A loss of electrons or a raising of the oxidation state.
oxidizing agent
A substance that takes electrons in a chemical reaction.
potentiometer
A device that measures electric potential by balancing it with a known potential of the opposite sign. A potentiometer is designed to draw much less current from the circuit being measured.
power
Energy expended (work done) per unit time. SI unit is J/s = W (watts)
redox reaction
A chemical reaction in which electrons are transferred from one element to another.
reducing agent
A substance that donates electrons in a chemical reaction.
reductant
Reducing agent.
reduction
A gain of electrons or a lowering of the oxidation state.
resistance
R, A measure of the retarding force opposing the flow of electric current. SI unit is ohm.
salt bridge
A conducting ionic medium in contact with two electrolyte solutions. It allows ions to flow without allowing immediate diffusion of one electrolyte solution into the other.
standard reduction potential
The voltage that would be measured when a hypothetical cell containing the desired half-reaction (with all species present at unit activity) is connected to a standard hydrogen electrode anode.
volt
Unit of electric potential difference. If the potential difference between two points is one volt, then one joule of energy is required to move one coulomb of charge between the two points.
watt
SI unit of power equal to an energy flow of one joule per second.
