General Chemistry (CHEM 111) - Chapter 4 Chemical Reactions and Solution Stoichiometry

Flashcards covering key vocabulary terms from the lecture on Chemical Reactions and Solution Stoichiometry, including solutions, electrolytes, reaction types, titration, and redox chemistry.

Chemical reactions

Involve the exchange of ions, atoms, and/or electrons between reacting compounds.

Solution

A homogeneous mixture of two or more substances.

Solvent

The substance in which dissolution takes place and is generally present in the largest amount.

Solute

The substance being dissolved in a solution.

Aqueous solution

A solution where water is the solvent.

Solvated ions

The constituent ions of ionic compounds that separate and become surrounded by solvent molecules when dissolved in a solvent.

Electrolytes

Substances (like NaCl) that form hydrated ions when dissolved in water, increasing the electrical conductivity of water.

Nonelectrolyte

A substance (like C6H12O6) that does not form ions in solution and whose solutions do not conduct electricity.

Strong electrolytes

Compounds that dissociate 100% (completely) in water to form hydrated ions.

Weak electrolytes

Compounds that do not dissociate completely (less than 100%) in water.

Precipitate

An insoluble ionic compound that forms when other ionic compounds do not dissolve in water.

Solubility rules

Allow us to predict the solubility of ionic compounds in water.

Soluble compounds

Ionic compounds that dissolve to the extent of 1 gram or more per 100 grams of water.

Precipitation reactions

Reactions where one or both products are insoluble in water, often also called double displacement or exchange (metathesis) reactions.

Double displacement (metathesis) reaction

A reaction where reactants swap partners, often resulting in a precipitation reaction if one product is insoluble.

Complete ionic equation

An equation that shows all soluble ionic compounds as their separated ions in solution.

Spectator ions

Ions that do not participate directly in a chemical reaction and appear unchanged on both sides of a complete ionic equation.

Net ionic equation (NIE)

An equation that shows only the ions that participate in the reaction by omitting spectator ions.

Acid

A species that generates H+(aq) ions (hydronium) when dissolved in water.

Strong acids

Acids that ionize 100% in aqueous solutions.

Weak acids

Acids that ionize less than 100% in aqueous solutions.

Base

A species that generates OH-(aq) ions (hydroxide) when dissolved in water.

Strong bases

Bases that ionize 100% in aqueous solutions.

Weak bases

Bases that ionize less than 100% in aqueous solutions.

Acid-Base (Neutralization) Reactions

Reactions between acids and bases that always result in a salt and water.

Ion-Exchange Reactions

A general category of reactions that include precipitation reactions and neutralization reactions, where ions are exchanged between compounds.

Molarity (M)

A measure of concentration defined as the amount of solute (in moles) dissolved in exactly 1 liter of solvent (moles/liter).

Direct Method (solution preparation)

A method generally used to prepare solutions with a relatively high amount of solute, by weighing the solute and dissolving it in a solvent.

Dilution Method (solution preparation)

A method used to prepare very dilute solutions by diluting a more concentrated stock solution, using the formula Mstock Vstock = Mdil Vdil.

Stock solution

A more concentrated solution from which a dilute solution can be prepared.

pH

A measure of H+(aq) or H3O+ (hydronium ion) concentration in a solution, indicating its acidity or basicity (pH = -log [H3O+]).

Acid-Base Titrations

An application of stoichiometry where a solution of known concentration (titrant) is used to analyze a solution of unknown concentration (analyte).

Equivalence point (titration)

The point in a titration when the moles of H+ ions equal the moles of OH- ions, resulting in a neutral solution ([H+] = [OH-]).

Gas Forming Reactions

Chemical reactions in which one of the products is a gas, such as ammonia (NH3) from ammonium salts with strong bases, or carbon dioxide (CO2) from metal carbonates with strong acids.

Oxidation-Reduction (Redox) Reactions

Chemical reactions that involve the transfer of electrons from one reactant to another.

Oxidation

The loss of one or more electrons from a chemical species.

Reduction

The gain of one or more electrons by a chemical species.

Reducing agents (reductants)

Elements or species that get oxidized (lose electrons) in a redox reaction.

Oxidizing agents (oxidants)

Elements or species that get reduced (gain electrons) in a redox reaction.

Oxidation number (Oxidation state)

A number that represents the hypothetical charge an atom would have if all bonds were ionic, primarily used to identify electron transfer in redox reactions.

Oxidation number of a pure element

Zero.

Oxidation number of a monoatomic ion

Equal to the ion's charge.

Oxidation number of halogens (in compounds)

-1, except when combined with oxygen or fluorine where Cl, Br, and I can be positive.

Oxidation number of oxygen (in compounds)

-2, except in peroxides (O2^2-) where it is -1.

Oxidation number of hydrogen (in compounds)

+1 when combined with nonmetals, -1 when combined with metals.

Sum of oxidation numbers (neutral compound)

Zero.

Sum of oxidation numbers (ion)

Equal to the overall charge on the ion.