Chemical Reactions: Types, Evidence, and Balancing

Vocabulary flashcards covering key concepts from the notes on chemical reactions, types, evidence, and balancing.

Chemical reaction

A process in which one or more reactants undergo a change to form one or more new substances (products).

Reactants

The starting substances that participate in a chemical reaction.

Products

The substances formed as a result of a chemical reaction.

Color change

A visible change in color indicating a chemical reaction.

Gas formation (bubbles)

Visible production of gas during a reaction (bubbles).

Precipitate

A solid that forms and settles out of solution during a chemical reaction.

Heat change

Release or absorption of heat (exothermic or endothermic) during a reaction.

Conservation of mass

Mass cannot be created or destroyed in a chemical reaction; total mass of reactants equals total mass of products.

Balanced chemical equation

An equation in which the same number of each type of atom appears on both sides.

Coefficient

A number placed in front of a formula in a chemical equation to balance atoms.

States of matter in equations

The phases of reactants and products (solid, liquid, gas, aqueous) indicated by symbols (s, l, g, aq).

Combination (Synthesis) reaction

A reaction where two or more substances combine to form a single product (A + B → AB).

Decomposition reaction

A reaction where one compound breaks down into two or more substances (AB → A + B).

Single displacement (replacement) reaction

A more reactive element replaces a less reactive element in a compound (AB + C → AC + B).

Double displacement (double replacement) reaction

Two compounds exchange ions to form two new compounds (AB + CD → AD + CB).

Combustion reaction

A hydrocarbon reacting with oxygen to form carbon dioxide and water (complete combustion yields CO2 and H2O).

Acid-base reaction

A reaction between an acid and a base to form a salt and water (neutralization).

Foil method

A way to predict products in double displacement reactions by swapping first and last ions (like FOIL in algebra).

Fire triangle

Three elements required for burning: fuel, oxygen, and an ignition source.

Polyatomic ions balancing

Balancing equations by treating polyatomic ions as a single unit to simplify balancing.

Polyatomic ion balancing (unit rule)

Balance with polyatomic ions as a unit, e.g., balance PO4^3− as a single unit.

Balanced equation check

Verifying that the equation has the same number of each atom on both sides.

Balancing by inspection

Trial-and-error method of balancing equations by adjusting coefficients.

Law of Conservation of Mass (Lavoisier)

Mass is neither created nor destroyed in a chemical reaction.

State symbols (s, l, g, aq)

Notation indicating the phase of each substance in a chemical equation.

Aqueous (aq)

A substance dissolved in water; represented as (aq) in equations.

Hydrocarbon

A compound composed of hydrogen and carbon; commonly involved in combustion.

Reaction conditions

Conditions such as temperature, pressure, and catalysts under which a reaction occurs.