Classifying Chemical Reactions Summary

Summary and Key Ideas

Classifying Chemical Reactions

Chemical reactions are classified according to similar patterns of behavior. A large number of important reactions are included in three categories: precipitation, acid-base, and oxidation-reduction (redox). Precipitation reactions involve the formation of one or more insoluble products. Acid-base reactions involve the transfer of hydrogen ions between reactants.

Redox reactions involve a change in oxidation number for one or more reactant elements. Writing balanced equations for some redox reactions that occur in aqueous solutions is simplified by using a systematic approach called the half-reaction method.

Glossary

Acid

substance that produces H3O⁺ when dissolved in water

Acid-base reaction

reaction involving the transfer of a hydrogen ion between reactant species

Base

substance that produces OH⁻ when dissolved in water

Combustion reaction

vigorous redox reaction producing significant amounts of energy in the form of heat and, sometimes, light

Half-reaction

an equation that shows whether each reactant loses or gains electrons in a reaction.

Insoluble

of relatively low solubility; dissolving only to a slight extent

Neutralization reaction

reaction between an acid and a base to produce salt and water

Oxidation

process in which an element’s oxidation number is increased by loss of electrons

Oxidation-reduction reaction

(also, redox reaction) reaction involving a change in oxidation number for one or more reactant elements

Oxidation number

(also, oxidation state) the charge each atom of an element would have in a compound if the compound were ionic

Oxidizing agent

(also, oxidant) substance that brings about the oxidation of another substance, and in the process becomes reduced

Precipitate

insoluble product that forms from reaction of soluble reactants

Precipitation reaction

reaction that produces one or more insoluble products; when reactants are ionic compounds, sometimes called double-displacement or metathesis

Reduction

process in which an element’s oxidation number is decreased by gain of electrons

Reducing agent

(also, reductant) substance that brings about the reduction of another substance, and in the process becomes oxidized

Salt

ionic compound that can be formed by the reaction of an acid with a base that contains a cation and an anion other than hydroxide or oxide

Single-displacement reaction

(also, replacement) redox reaction involving the oxidation of an elemental substance by an ionic species

Soluble

of relatively high solubility; dissolving to a relatively large extent

Solubility

the extent to which a substance may be dissolved in water, or any solvent

Strong acid

acid that reacts completely when dissolved in water to yield hydronium ions

Strong base

base that reacts completely when dissolved in water to yield hydroxide ions

Weak acid

acid that reacts only to a slight extent when dissolved in water to yield hydronium ions

Weak base

base that reacts only to a slight extent when dissolved in water to yield hydroxide ions