APChem - Chapter 3 Vocabulary

Stoichiometry

the relationships among the quantities of reactants and products involved in chemical reactions

Reactant

a starting substance in a chemical reaction; it appears to the left of the arrow in a chemical equation

Product

a substance produced in a chemical reaction; it appears to the right of the arrow in a chemical equation

Combination reactions

a chemical reactions in which two or more substances combine to form a single product (ex: A + B —> C)

Decomposition reactions

a chemical reactions in which a single compound reacts to give two or more products (ex: C —> A + B)

Combustion reactions

a chemical reaction that proceeds with the evolution of heat and usually, a flame; mostly involve a reaction with oxygen

Formula weight (FW)

the sum of the atomic weights (AW) of the atoms in the chemical formula of the substance

Molecular weight

the sum of the atomic weights (AW) of the atoms represented by their chemical formula for a molecule

Elemental composition

the percentage composition of an element in a substance

mole

a collection of Avogadro's number (6.022 x 10²³) of objects

Molar mass

the mass of one mole of a substance in grams; it is numerically equal to the formula weight in atomic mass units

Limiting reactant

the reactant that is completely consumed in a reaction; the amount of product that can form is limited by the complete consumption of the limiting reactant

Excess reactant

the reactant that is left over from the reaction because there was no more of the limited reactant

theoretical yield

the quantity of product that is calculated to form when all of the limiting reagent reacts

Actual yield

the amount of product actually produced (almost always less than, but never greater than, the the theoretical yield)