Unit 3 Chemistry Review

Formula mass/ Molecular Mass

The sum of the atomic masses of the atoms in a molecule

The Mole

a unit of measurement pertaining to the number of molecules in a sample.

Avogardo’s Number

The number of items in a mole which is approximately 6.022 × 10²³

Molar Mass

The mass of one mole of a substance, usually expressed in grams per mole (g/mol), which is numerically equal to the molecular or formula mass of the substance. uses amu as a conversion factor.

Empirical Formula from moles

divide each amount of moles for an element by the smallest number of moles to obtain the simplest ratio of the elements in a compound.

Empirical formula from mass

mass x 1 mol/ molar mass of the substance and then divide your answer by the smallest number

Empirical Formula from Percent By Mass

Convert percent to grams, assume 100 g sample, and then find moles of each element before dividing by the smallest number of moles.

Finding Molecular formulas from Empirical Formula

divide molar mass by empirical formula mass and you multiply your answer by the subscripts of the empirical formula to get the formula of the compound.

A solution

Contains one component with a concentration that is significantly greater than all other components( called a solvent)

A solution in which water is a solvent is called an ——- ——-

Aqueous solution

A Solute

A component of a solution that is typically present at a much lower concentration than the solvent