Chapter 8: Chemical Reactions and Stoichiometry

Vocabulary flashcards covering key definitions and foundational concepts of chemical equations, reaction types, mass conservation, stoichiometry, combustion analysis, limiting reagents, and reaction yields.

Chemical Equation

A shorthand description of a chemical reaction that uses chemical symbols and formulas for elements and compounds, letters in parentheses for physical states, and numbers indicating relative quantities.

Reactants

The starting substances in a chemical reaction, written on the left side of the chemical equation.

Products

The substances formed during a chemical reaction, written on the right side of the chemical equation.

Stoichiometric Coefficients

The numbers placed in front of chemical symbols and formulas representing the number of moles of each substance; if no number is shown, the coefficient is $1$.

Aqueous ($(aq)$)

A state designation indicating that a substance is dissolved in water.

Law of Conservation of Mass

A law stating that total mass remains constant during a chemical reaction; matter cannot be created or destroyed, meaning the mass of reactants must exactly match the mass of products.

Mass Balance

The condition where the total mass of the reactants exactly matches the total mass of the products in a chemical process.

Combination Reaction (Synthesis)

A type of chemical reaction where two or more reactants combine to form a single product.

Decomposition Reaction

A type of chemical reaction where a single reactant breaks apart to form two or more products.

Combustion Reaction

A chemical reaction in which a substance burns in the presence of oxygen ($O_2$).

Combustion Analysis (Elemental Analysis)

An experimental technique where a measured amount of a compound is burned in excess $O_2$, and the masses of resulting products such as $CO_2$ and $H_2O$ are used to calculate the moles and masses of each element present.

Empirical Formula

The simplest whole-number ratio of the moles of elements present in a compound.

Stoichiometry

Calculations of quantitative relationships based on balanced chemical reactions to determine how much reactant is needed or how much product is formed.

Mole Ratio

The ratio between the amounts in moles of any two compounds or elements involved in a chemical reaction, derived directly from the coefficients of the balanced equation.

Limiting Reagent

The reactant that runs out first in a reaction, thereby producing the smallest amount of product and determining how much product can be formed.

Theoretical Yield

The maximum amount of product that can be formed in a chemical reaction based on the limiting reagent, generally reported in grams.

Actual Yield

The amount of product recovered and measured during an experiment.

Percent Yield

The efficiency of a chemical reaction calculated as: $\frac{\text{Actual yield}}{\text{Theoretical yield}} \times 100$.

Factors Decreasing Product Yield

Circumstances that prevent reactions from producing the theoretical maximum yield: impure reactants, incomplete reaction, unrecovered product, and side reactions.