Glossary
Acid-Base Reactions
Chemical reactions involving the transfer of protons (H⁺) between reactants, often forming a salt and water.
Example:
When you mix hydrochloric acid (HCl) with sodium hydroxide (NaOH), a classic acid-base reaction occurs, neutralizing each other.
Concentration of Ions
The amount of a specific ion present in a given volume of solution, typically expressed in molarity (moles/liter).
Example:
After a precipitation reaction, calculating the concentration of ions remaining in solution helps determine which species are still dissolved and at what amount.
Insoluble
Describes a substance that does not dissolve significantly in a given solvent, typically water, forming a solid precipitate.
Example:
Chalk (calcium carbonate) is largely insoluble in water, which is why it doesn't disappear when you put it in a glass of water.
Limiting Reactant
The reactant in a chemical reaction that is completely consumed first, thereby determining the maximum amount of product that can be formed.
Example:
If you're making s'mores and run out of marshmallows before chocolate or graham crackers, the marshmallows are the limiting reactant because they stop you from making more.
Molarity
A measure of the concentration of a solute in a solution, defined as the number of moles of solute per liter of solution.
Example:
A 0.100 M NaCl solution means there are 0.100 moles of NaCl dissolved in every liter of that solution, indicating its molarity.
Net Ionic Equations
Chemical equations that show only the ions and molecules directly involved in a chemical reaction, omitting spectator ions.
Example:
For the reaction of silver nitrate and sodium chloride, the net ionic equation focuses only on Ag⁺(aq) + Cl⁻(aq) → AgCl(s), showing the actual formation of the precipitate.
Oxidation-Reduction (Redox) Reactions
Chemical reactions characterized by the transfer of electrons between chemical species, where one substance is oxidized (loses electrons) and another is reduced (gains electrons).
Example:
The rusting of iron is a redox reaction where iron loses electrons to oxygen, forming iron oxide.
Precipitate
An insoluble solid that forms and separates from a solution during a chemical reaction.
Example:
When hard water is boiled, calcium carbonate can form a solid precipitate that coats the inside of kettles.
Precipitation Reactions
Reactions that occur when two or more aqueous solutions are mixed, leading to the formation of an insoluble solid product called a precipitate.
Example:
Mixing solutions of silver nitrate and sodium chloride results in a precipitation reaction, forming solid silver chloride.
Solubility Rules
A set of guidelines used to predict whether an ionic compound will dissolve in water or form a precipitate.
Example:
According to solubility rules, all compounds containing nitrate ions (NO₃⁻) are soluble, meaning they will not form a precipitate.
Spectator Ions
Ions present in a solution that do not participate in the chemical reaction and remain unchanged on both sides of a complete ionic equation.
Example:
In the reaction between NaCl and AgNO₃, the Na⁺ and NO₃⁻ ions are spectator ions because they remain dissolved in solution before and after the precipitate forms.
Stoichiometry
The branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions.
Example:
Using stoichiometry, you can calculate exactly how much oxygen is needed to completely burn a certain amount of methane.