Moles and Molar Mass

• The mole (mol) is the amount of a substance that contains the same number of particles as atoms in exactly 12 grams of carbon-12.

• the number of particles (atoms or molecules or ions) per mole is called Avogadro’s number and is numerically equal to 6.022 × 10^23 particles.

• The mass in grams of one mole of a substance is the molar mass.

Percent Composition and Empirical Formulas

• convert each to moles, divide each by the smallest number, then use an appropriate multiplier if needed.

• The empirical formula tells us what elements are present in the compound and the simplest whole-number ratio of elements.

Reaction Stoichiometry

• stoichiometry, the calculation of the amount (mass, moles, particles) of one substance in chemical reaction through the use of another.

• The coefficients in a balanced chemical equation define the mathematical relationship between the reactants and products, and allow the conversion from moles of one chemical species in the reaction to another.

Limiting Reactants

• The reactant that is used up first is called the limiting reactant (L.R.).

Percent Yield

• The maximum amount of product formed is called the theoretical yield.

• the amount that is actually formed is the actual yield

• The percent yield (% yield) is the actual yield divided by the theoretical yield, and the result is multiplied by 100% to generate a percentage

Molarity and Solution Calculations

• Solutions are homogeneous mixtures composed of a solute (substance present in smaller amounts) and a solvent (substance present in larger amounts).

• concentration, the amount of solute dissolved in the solvent.

• Molarity (M) is defined as the moles of solute per liter of solution: