Exam 3 Important Terms

What is an alkaline battery?

An alkaline battery is a primary battery similar to a dry cell that uses an alkaline (often potassium hydroxide) electrolyte; it is designed to be an improved replacement for the dry cell, with more energy storage and less electrolyte leakage.

What is an anode?

The anode is the electrode in an electrochemical cell at which oxidation occurs.

What is a battery?

A battery is a single or series of galvanic cells designed for use as a source of electrical power.

What is a cathode?

The cathode is the electrode in an electrochemical cell at which reduction occurs.

What is cathodic protection?

Cathodic protection is an approach to preventing corrosion of a metal object by connecting it to a sacrificial anode composed of a more readily oxidized metal.

What is cell notation (schematic)?

Cell notation (schematic) is a symbolic representation of the components and reactions in an electrochemical cell.

What is cell potential (E_cell)?

Cell potential (E_cell) is the difference in potential of the cathode and anode half-cells.

What is a concentration cell?

A concentration cell is a galvanic cell comprising half-cells of identical composition but differing in the concentration of one redox reactant or product.

What is corrosion?

Corrosion is the degradation of metal via a natural electrochemical process.

What is a dry cell?

A dry cell is a primary battery, also called a zinc-carbon battery, based on the spontaneous oxidation of zinc by manganese(IV).

What is electrode potential (E_X)?

Electrode potential (E_X) is the potential of a cell in which the half-cell of interest acts as a cathode when connected to the standard hydrogen electrode.

What is electrolysis?

Electrolysis is a process using electrical energy to cause a nonspontaneous process to occur.

What is an electrolytic cell?

An electrolytic cell is an electrochemical cell in which an external source of electrical power is used to drive an otherwise nonspontaneous process.

What is Faraday’s constant (F)?

Faraday’s constant (F) is the charge on 1 mol of electrons; F = 96,485 C/mol e−.

What is a fuel cell?

A fuel cell is a device similar to galvanic cells that requires a continuous feed of redox reactants; it is also called a flow battery.

What is a galvanic (voltaic) cell?

A galvanic (voltaic) cell is an electrochemical cell in which a spontaneous redox reaction takes place.

What is galvanization?

Galvanization is a method of protecting iron or similar metals from corrosion by coating with a thin layer of more easily oxidized zinc.

What is a half cell?

A half cell is a component of a cell that contains the redox conjugate pair (“couple”) of a single reactant.

What is an inert electrode?

An inert electrode is an electrode that conducts electrons to and from the reactants in a half-cell but is not itself oxidized or reduced.

What is a lead acid battery?

A lead acid battery is a rechargeable battery commonly used in automobiles, typically comprising six galvanic cells based on Pb half-reactions in acidic solution.

What is a lithium ion battery?

A lithium ion battery is a widely used rechargeable battery commonly used in portable electronic devices, based on lithium ion transfer between the anode and cathode.

What is the Nernst equation?

The Nernst equation relates the potential of a redox system to its composition.

What is a nickel-cadmium battery?

A nickel-cadmium battery is a rechargeable battery based on Ni/Cd half-cells with applications similar to those of lithium ion batteries.

What is a primary cell?

A primary cell is a nonrechargeable battery, suitable for single use only.

What is a sacrificial anode?

A sacrificial anode is an electrode constructed from an easily oxidized metal, often magnesium or zinc, used to prevent corrosion of metal objects via cathodic protection.

What is a salt bridge?

A salt bridge is a tube filled with inert electrolyte solution.

What is a secondary cell?

A secondary cell is a battery designed to allow recharging.

What is standard cell potential (E°_cell)?

Standard cell potential (E°_cell) is the cell potential when all reactants and products are in their standard states (1 bar or 1 atm for gases; 1 M for solutes), usually at 298.15 K.

What is standard electrode potential (E°_X)?

Standard electrode potential (E°_X) is the electrode potential measured under standard conditions (1 bar or 1 atm for gases; 1 M for solutes), usually at 298.15 K.

What is the standard hydrogen electrode (SHE)?

The standard hydrogen electrode (SHE) is a half-cell based on hydrogen ion production, assigned a potential of exactly 0 V under standard state conditions, used as the universal reference for measuring electrode potential.

What is the common ion effect?

The effect on equilibrium when a substance with an ion in common with the dissolved species is added to the solution; it causes a decrease in the solubility of an ionic species or a decrease in the ionization of a weak acid or base.

What is a complex ion?

An ion consisting of a central atom surrounded by molecules or ions called ligands via coordinate covalent bonds.

What is a coordinate covalent bond?

A covalent bond in which both electrons originated from the same atom; also known as a dative bond.

What are coupled equilibria?

A system characterized by the simultaneous establishment of two or more equilibrium reactions sharing one or more reactant or product.

What is a dissociation constant (K_d)?

The equilibrium constant for the decomposition of a complex ion into its components.

What is a formation constant (K_f)?

Also known as the stability constant, it is the equilibrium constant for the formation of a complex ion from its components.

What is a Lewis acid?

Any species that can accept a pair of electrons and form a coordinate covalent bond.

What is a Lewis acid-base adduct?

A compound or ion that contains a coordinate covalent bond between a Lewis acid and a Lewis base.

What is Lewis acid-base chemistry?

Reactions involving the formation of coordinate covalent bonds.

What is a Lewis base?

Any species that can donate a pair of electrons and form a coordinate covalent bond.

What is a ligand?

A molecule or ion acting as a Lewis base in complex ion formation; it bonds to the central atom of the complex.

What is molar solubility?

The solubility of a compound expressed in units of moles per liter (mol/L).

What is selective precipitation?

A process in which ions are separated using differences in their solubility with a given precipitating reagent.

What is the solubility product constant (K_sp)?

The equilibrium constant for the dissolution of an ionic compound.

What is entropy (S)?

A state function that is a measure of the matter and/or energy dispersal within a system, determined by the number of system microstates; often described as a measure of the disorder of the system.

What is Gibbs free energy change (G)?

A thermodynamic property defined in terms of system enthalpy and entropy; all spontaneous processes involve a decrease in G.

What is a microstate?

A possible configuration or arrangement of matter and energy within a system.

What is a nonspontaneous process?

A process that requires continual input of energy from an external source.

What is a reversible process?

A process that takes place so slowly as to be capable of reversing direction in response to an infinitesimally small change in conditions; a hypothetical construct that can only be approximated by real processes.

What is the second law of thermodynamics?

All spontaneous processes involve an increase in the entropy of the universe.

What is a spontaneous change?

A process that takes place without a continuous input of energy from an external source.

What is standard entropy (S°)?

Entropy for one mole of a substance at 1 bar pressure; tabulated values are usually determined at 298.15 K.

What is standard entropy change (ΔS°)?

The change in entropy for a reaction calculated using the standard entropies.

What is standard free energy change (ΔG°)?

The change in free energy for a process occurring under standard conditions (1 bar pressure for gases, 1 M concentration for solutions).

What is standard free energy of formation (ΔG°f)?

The change in free energy accompanying the formation of one mole of substance from its elements in their standard states.

What is the third law of thermodynamics?

The entropy of a perfect crystal at absolute zero (0 K) is zero.