CHEM121 - CH 8 VOCAB

molarity (M)

the number of moles of solute in a volume of solution; n/V

standard solution

a solution of accurately known concentration used in chemical analysis

dilution

the process of reducing solute concentration by adding more solvent to a solution

absorbance (A)

a measure of the quantity of light a solution absorbs

Beer’s law

relates absorbance to three quantities: concentration, the path length that the light travels through the solution, and molar absorptivity (ε)

molar absorptivity (ε)

a measure of how well a compound or ion absorbs light

calibration curve

a graph showing how a measurable property varies for a set of standard samples that can later be used to identify an unknown concentration from a measured absorbance

electrode

a solid electrical conductor used to make contact with a solution or other nonmetallic component of an electrical circuit

electrolyte

a solute that produces ions in solution, enabling its solutions to conduct electricity

strong electrolyte

a substance that dissociates completely when it dissolves in water

nonelctrolyte

a molecular substance that does not ionize when it dissolves in water

hydronium ions (H₃O⁺)

an H⁺ ion plus a water molecule, H₂O; the form in which the hydrogen ion is found in aqueous solution

weak electrolyte

a substance that only partly ionizes when it dissolves in water

Brønsted–Lowry acid

proton donor

Brønsted–Lowry base

proton acceptor

neutralization reaction

a reaction that takes place when an acid reacts with a base and produces a solution of a salt in water

salt

the product of a neutralization reaction, made up of the cation of the base in the reaction plus the anion of the acid

molecular equation

a balanced equation describing a reaction in solution in which the reactants and products are written as neutral compounds

overall ionic equation

a balanced equation that shows all the species, both ionic and molecular, present in a reaction occurring in an aqueous solution

net ionic equation

a balanced equation that describes the actual reaction taking place in aqueous solution; it is obtained by eliminating the spectator ions from the overall ionic equation

spectator ion

an ion present in a reaction vessel when a chemical reaction takes place but is unchanged by the reaction; they appear in an overall ionic equation but not in a net ionic equation

strong acid

an acid that completely ionizes in aqueous solution

weak acid

a weak electrolyte that only partially ionizes in aqueous solution

carboxylic acid

a compound containing the -COOH functional group

strong base

a base that completely dissociates into ions in aqueous solution

weak base

a base that is a weak electrolyte and has a limited capacity to accept protons

amphirotic

describes a substance that can behave as either a proton acceptor or a proton donor

titration

an analytical method of determining the concentration of a solute in a sample by reacting the solute with a solution of known concentration

titrant

the standard solution added to the sample in a titration

analyte

the substance whose concentration is to determined in a chemical analysis

equivalence point

the point in a titration at which just enough titrant has been added to react with all the analyte in the sample

end point

the point in a titration at which a color change or other signal indicates that enough titrant has been added to react with all the analyte in the sample

precipitate

a solid product formed from a reaction in solution

precipitation reaction

a reaction in which soluble reactants form a product that has limited solubility

saturated solution

a solution that contains the maximum concentration of a solute possible at a given temperature

unsaturated solution

a solution that contains less than the maximum quantity of solute predicted to be soluble in a given volume of solution at a given temperature

supersaturated solution

a solution that contains more than the maximum quantity of solute predicted to be soluble in a given volume of solution at a given temperature

oxidation

a chemical change in which an element loses electrons; the oxidation number of the element increases

reduction

a chemical change in which an element gains electrons; the oxidation number of the element decreases

oxidation number (O.N) or oxidation state

a numerical value (+,0,-) based on the number of electrons than an atom gains or loses when it forms an ion or that it shares when it forms a covalent bond with an atom of another element

oxidizing agents

a reactant that accepts electrons from another in a redox reaction, thereby oxidizing the other reactant; the oxidizing agent is reduced in the reaction

reducing agent

a reactant that donates electrons to another in a redox reaction, thereby reducing the other reactant; the reducing agent is oxidized in the reaction

half-reaction

one of the halves of an oxidation-reduction reaction; one half-reaction is the oxidation component, and the other is the reduction component

activity series

a high-to-low ranking of metals on the basis of their strengths as reducing agents