A reaction that reduces the yield of the main product by forming by-products
empirical formula
A chemical formula that uses the smallest whole-number subscripts to give the proportions by atoms of the different elements present
excess reactant
The reactant left over once the limiting reactant is used up.
formula mass
The sum of the atomic masses (in u) of all of the atoms represented in a chemical formula. Often used with units of g mol-1 to represent masses of ionic substances.
limiting reactant
The reactant that determines how much product can form when nonstoichiometric amounts of reactants are used.
main reaction
The desired reaction between the reactants as opposed to competing reactions that give by-products.
Molar mass
The mass of one mole of a substance; the mass in grams equal to the sum of the atomic masses of the atoms in a substance, with units of g mol-1
molecular formula
A chemical formula that gives the actual composition of one molecule.
molecular mass
The sum of the atomic masses (in u) of all of the atoms represented in a molecular chemical substance; also called the molecular weight. May be used with units of g mol-1.
mole
The SI unit for amount of substance; the formula mass in grams of an element or compound; an amount of a chemical substance that contains 6.022 × 1023 formula units.
percentage composition
A list of the percentages by weight of the elements in a compound.
percentage yield
The ratio (taken as a percent) of the mass of product obtained to the mass calculated from the reaction's stoichiometry.
side reaction
A reaction the occurs simultaneously with another reaction (the main reaction) in the same mixture to produce by-products
theoretical yield
The yield of a product calculated from the reaction's stoichiometry.