Stoichiometry & General Concepts

Vocabulary flashcards covering core concepts, definitions, reaction types, molar calculations, and yields from Chapter 2: Stoichiometry & General Concepts.

Mole

The SI unit for the amount of any substance, defined as the number of atoms in exactly $12\,g$ of pure carbon-12.

Avogadro's Number

The number of molecules or atoms in one mole of any substance, equal to $6.022 \times 10^{23}$.

Molar Mass

The sum of the mass of all atoms found in one mole's worth of a substance, expressed in units of $g\cdot mol^{-1}$.

Molecular Formula

A chemical formula that tells the exact number of atoms of each element found in a molecule.

Percent Composition

The percent of a compound's total mass that is made up by a specific element.

Empirical Formula

The simplest, or most reduced, ratio of atoms of each element in a compound.

Subscript

The number of atoms of an element present in each molecule, which cannot be changed when balancing a chemical equation.

Coefficient

A number placed before a chemical formula in an equation to represent quantity and balance the total number of atoms.

Limiting Reagent

The reactant that determines how much product is formed and is completely used up first in a chemical reaction.

Excess Reagent

The leftover reactant in a chemical reaction that is not completely consumed.

Density

An intrinsic physical property of a substance defined as mass per unit volume ($\rho = \frac{m}{V}$), typically expressed in units of $g\cdot cm^{-3}$.

Actual Yield

The real quantity of product resulting experimentally from a chemical reaction.

Theoretical Yield

The maximum calculated quantity of product that can be expected from an ideal chemical reaction based on stoichiometry.

Percent Yield

A measure of reaction efficiency, calculated as actual yield divided by theoretical yield multiplied by $100\%$.

Element

A pure substance composed of one type of atom that cannot be broken down into other substances through physical or chemical reactions.

Compound

A substance formed when two or more atoms from different elements combine in a fixed proportion.

Law of Constant Composition

The principle stating that elements within a specific compound always combine in a fixed proportion.

Physical Reaction

A process that alters physical properties or phase of matter without forming or destroying chemical bonds or creating new substances.

Chemical Reaction

A process in which intramolecular bonds between atoms are created or destroyed, resulting in new substances with distinct properties.

Synthesis Reaction

A chemical reaction where two or more atoms or molecules combine to form a single compound, usually releasing energy.

Decomposition Reaction

A chemical reaction where a compound breaks down into two or more products, usually requiring an input of energy.

Single Displacement Reaction

A chemical reaction in which one element is replaced by another element in a compound.

Double Displacement Reaction

A chemical reaction involving the exchange of bonds between two reacting chemical species, such as neutralization and precipitation reactions.

Combustion Reaction

A chemical reaction in which a substance reacts with $O_2(g)$ gas to produce light and heat.