Chemical Reactions and Reaction Stoichiometry

A set of vocabulary flashcards covering the fundamental concepts of chemical equations, reaction types, the mole concept, stoichiometry, and reaction yields based on Chapter 3 of 'Chemistry: The Central Science'.

Reactants

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

Products

The ending materials in a chemical reaction, typically written on the right side of a chemical equation.

Law of Conservation of Mass

The principle followed when balancing equations to ensure that the mass of reactants equals the mass of products.

Coefficients

Numbers placed in front of chemical formulas in an equation to balance it, representing the relative number of moles or molecules; unlike subscripts, these can be changed during balancing.

(aq)

A symbol written in parentheses to the right of a formula indicating that a substance is dissolved in aqueous (water) solution.

Combination Reactions

A type of chemical reaction where two or more substances react to form one single product, represented by the pattern $A + B \rightarrow C$.

Decomposition Reactions

A type of chemical reaction where one substance breaks down into two or more substances, often occurring when a compound is heated.

Combustion Reactions

Rapid reactions that produce a flame and most often involve oxygen in the air as a reactant.

Formula Weight (FW)

The sum of the atomic weights for the atoms in a chemical formula, such as $23.0\,amu$ for sodium ($Na$).

Molecular Weight (MW)

The sum of the atomic weights of the atoms in a molecule; for molecular substances, this is the same as the formula weight.

Percent Composition

The percentage by mass of each element in a compound calculated as: $\frac{(\text{number of atoms of element}) \times (\text{atomic weight of element})}{\text{formula weight of compound}} \times 100\%$.

Mole (mol)

The amount of particles found in exactly $12\,g$ of $C-12$.

Avogadro’s Number

The number of particles in one mole, equal to $6.02 \times 10^{23}$ atoms or molecules.

Molar Mass

The mass in grams of $1\,mol$ of a substance (expressed in $g/mol$), which is numerically equal to the formula weight in $amu$.

Empirical Formula

The simplest chemical formula of a compound determined from the mole ratio of its constituent elements.

Stoichiometry

The calculation of relative quantities of reactants and products in chemical reactions using the mole ratio from a balanced equation.

Limiting Reactant

The reactant that is completely consumed first in a chemical reaction, thereby limiting the amount of product that can be formed.

Excess Reagent

The reactant that remains in the reaction mixture after the limiting reactant has been completely consumed.

Theoretical Yield

The maximum amount of product that can be produced in a chemical reaction as calculated through stoichiometry.

Actual Yield

The amount of product that is actually produced and measured in a laboratory setting.

Percent Yield

The ratio of the actual yield to the theoretical yield, expressed as a percentage: $\frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$.