ChemVocab: Unit 4

Reactions in aqueous solutions

Solution

a homogeneous mixture of two or more substances

Solute

the substance present in a smaller amount

Solvent

the substance present in a larger amount

Aqueous Solutions

the solute initially is a liquid or a solid and the solvent is water

Electrolyte

a substance that, when dissolved in water, results in a solution that can conduct electricity

Nonelectrolyte

does not conduct electricity when dissolved in water

Dissociation

the breaking up of the compound into cations and anions

Hydration

the process in which an ion is surrounded by water molecules arranged in a specific manner

Reversible Reaction

the reaction can occur in both directions 

Precipitation Reaction

reaction that occurs in aqueous solution and results in the formation of an insoluble product, or precipitate

Precipitate

an insoluble solid that separates from the solution

Metathesis Reaction (double-replacement reaction)  

a reaction that involves the exchange of parts between the two compounds

Solubility

the maximum amount of solute that will dissolve in a given quantity of solvent at a specific temperature 

Molecular Equation

the formulas of the compounds are written as though all species existed as molecules or whole units

Ionic Equation

shows the dissolved species as free ions

Spectator Ions

 ions that are not involved in the overall reaction

Net Ionic Equation

shows only the species that actually take part in the reaction

Brønsted acid

a proton donor

Brønsted base

a proton acceptor

Hydronium Ion

hydrated proton (H₃O⁺)

Monoprotic Acids

each unit of the acid yields one hydrogen ion upon ionization

Diprotic Acid

each unit of the acid gives up two H+ ions

Triprotic Acid

yield three H+ ions

Neutralization Reaction

a reaction between an acid and a base

Salt

an ionic compound made up of a cation other than H+ and an anion other than OH^- or O^2-

Oxidation-Reduction (redox) Reaction

electron-transfer reactions

Half reaction

explicitly shows the electrons involved in a redox reaction

Oxidation Reaction

half-reaction that involves loss of electrons

Reduction Reaction

half-reaction that involved gain of electrons

Reducing Agent

donator of electrons

Oxidizing Agent

acceptor of electrons

Oxidation Number

number of charges the atom would have in a molecule (or an ionic compound) if electrons were transferred completely

Combination Reaction

a reaction in which two or more substances combine to form a single product

Decomposition Reaction

the breakdown of a compound into two or more components

Combustion Reaction

a reaction in which a substance reacts with oxygen, usually with the release of heat and light to produce a flame

Displacement Reaction

an ion (or atom) in a compound is replaced by an ion (or atom) of another element

Types of Displacement Reactions

hydrogen displacement, metal displacement, halogen displacement

Activity Series

a convenient summary of the results of many possible displacement reactions

Activity Series of Halogen Displacements

F₂>Cl₂>Br₂>I₂

Disproportionation Reaction

an element in one oxidation state is simultaneously oxidized and reduced

Concentration of a Solution

the amount of solute present in a given amount of solvent; or a given amount of solution

Molarity

the number of moles of solute per liter of solution

Molarity Formula

Molarity= moles of solute/liters of solution

Dilution

the procedure for preparing a less concentrated solution from a more concentrated one

Quantitative Analysis

the determination of the amount or concentration of a substance in a sample

Gravimetric Analysis

an analytical technique based on the measurement of mass

Standard Solution

a solution of accurately known concentration

Titration

a solution of accurately known concentration (standard solution) is added gradually to another solution of unknown concentration, until the chemical reaction between the two solutions is complete

Equivalence Point

 the point at which the acid has completely reacted with or been neutralized by the base

Indicators

substances that have distinctly different colors in acidic and basic media