% Comp, Stoichiometry, Empirical Formula, and Limiting Reactants

Percent Composition by mass

Percent Composition by mass

The percent that each element in a compound contributes to the total mass of the compound.

Empirical formula

Determined by the simplest whole-number ratio of every atom in the compound. It’s a formula showing the proportions of an element present in a compound.

Molecular formula

The actual formula for the molecule

Stoichiometry

Scientists perform chemical calculations or stoichiometry to measure the number of reactants and products in a chemical reaction.

Mole to Mole Stoichiometry

In mole to mole stoichiometry, we start with moles and end with moles.

Volume to Volume Stoichiometry

Equal volumes of all gases are the same at standard temperature and pressure (STP). You can get the volume ratios from the balanced equation.

Limiting Reactant

The reactant that is used up first in a chemical reaction

Excess Reactant

Reactants that are left over when the limiting reactant is gone

The theoretical yield

The amount of product that would be produced if the limiting reactant completely reacted.

The actual yield

The amount of product actually produced in the reaction.

The percentage yield

The ratio of actual yield to theoretical yield.