1. Empirical formula In chemistry, the empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound.chemistrychemical compoundatoms The empirical formula is used as standard for most ionic compounds, such as CaCl 2, and for macromolecules, such as SiO 2.CaCl 2macromoleculesSiO 2 Molecular formula identifies the number of each type of atom in a molecule (COVALENT COMPOUND)Molecular formula The structural formula also shows the structure of the molecule.structural formula

2. Steps Step 1: Change each percentage to an expression of the mass of each element in grams. That is, 48.64% C becomes 48.64 g C, 8.16% H becomes 8.16 g H, and 43.20% O becomes 43.20 g O. Step 2: Convert the amount of each element in grams to its amount in moles. Step 3: Divide each of the found values by the smallest of these values (SMALLEST number of MOLES) Step 4: In necessary, multiply these numbers by integers in order to get whole numbers; if an operation is done to one of the numbers, it must be done to all of them.

3. Determine the emperical formula for each of the following a. 8.04 g lithium, 91.96 g bromide b. 70.9 % potassium, 29.1 % sulfur c. 0.286 g magnesium, 0.143 g carbon, 0.571 g oxygen

4. Steps for Determining an Empirical Formula Start with the number of grams of each element, given in the problem. –If percentages are given, assume that the total mass is 100 grams so that the mass of each element = the percent given. Convert the mass of each element to moles using the molar mass from the periodic table. periodic table

5. Divide each mole value by the smallest number of moles calculated. Round to the nearest whole number. This is the mole ratio of the elements and is represented by subscripts in the empirical formula. –If the number is too far to round (x.1 ~ x.9), then multiply each solution by the same –factor to get the lowest whole number multiple. e.g. If one solution is 1.5, then multiply each solution in the problem by 2 to get 3. e.g. If one solution is 1.25, then multiply each solution in the problem by 4 to get 5.