Chapter 5: Classification and Balancing of Chemical Reactions

Vocabulary flashcards covering core terms and definitions from the Chapter 5 lecture on chemical equations, reaction types, and related principles.

Chemical Equation

An expression that uses symbols and formulas to represent a chemical reaction.

Law of Conservation of Mass

Principle stating that mass is neither created nor destroyed; atoms present in reactants equal those in products.

Reactant

A substance that undergoes change in a chemical reaction; written on the left side of the arrow.

Product

A substance formed in a chemical reaction; written on the right side of the arrow.

Coefficient

A whole number placed in front of a chemical formula to balance an equation and indicate relative amounts of substances.

State Symbols

Notations indicating physical state: (s) solid, (l) liquid, (g) gas, (aq) dissolved in water.

Balancing Chemical Equations

Adjusting coefficients so the number and kinds of atoms are identical on both sides of the reaction arrow.

Balancing Step 1

Write correct, unbalanced formulas for all reactants and products; never alter subscripts.

Balancing Step 2

Add appropriate coefficients, beginning with elements that appear in only one substance on each side.

Balancing Step 3

Check that each element has the same number of atoms on both sides of the equation.

Balancing Step 4

Reduce all coefficients to the lowest whole-number ratio.

Polyatomic Ion

A covalently bonded group of atoms carrying a net charge and acting as a single unit in reactions.

Precipitation Reaction

A reaction in which insoluble solid (precipitate) forms when cations and anions in solution exchange partners.

Precipitate

The insoluble solid produced during a precipitation reaction.

Solubility

The amount of a substance that dissolves in a given quantity of solvent at a specific temperature.

Solubility Guideline

If a potential product has low solubility, it will precipitate; if highly soluble, no precipitate forms.

Neutralization Reaction

Reaction between an acid and a base that produces water and an ionic compound called a salt.

Acid

A substance with one or more hydrogen ions (H⁺) attached to an anion (e.g., HCl, H₂SO₄).

Base

A group 1 or group 2 metal hydroxide containing OH⁻ ions (e.g., NaOH, Ca(OH)₂).

Salt (in Acid-Base Chemistry)

The ionic compound formed alongside water in a neutralization reaction.

Carbonate Neutralization

Acid + carbonate/bicarbonate → water + salt + carbon dioxide (CO₂).

Redox (Oxidation-Reduction) Reaction

A reaction involving transfer of electrons from one species to another.

Oxidation

Loss of electrons or an increase in oxidation state / addition of oxygen.

Reduction

Gain of electrons or a decrease in oxidation state / removal of oxygen.

Reducing Agent

Species that donates electrons, causes reduction, and is itself oxidized.

Oxidizing Agent

Species that accepts electrons, causes oxidation, and is itself reduced.

Alkali Metals

Group 1 elements; very strong reducing agents due to low ionization energies.

Reactive Nonmetals

Highly electronegative elements that act as powerful oxidizing agents by readily gaining electrons.

Ionic Equation

Chemical equation that explicitly shows all ions present in an aqueous reaction.

Spectator Ion

Ion that appears unchanged on both sides of an ionic equation and does not participate in the reaction.

Net Ionic Equation

An equation that includes only the ions and molecules directly involved in the chemical change, balanced for both mass and charge.