Chemical Formula’s

Chemical formula Used to express the composition of molecules and ionic compounds in terms of chemical symbols

Empirical Molecular Tells us which elements are present and in the simplest whole- number ratio of their atoms Based on observation or measurement Shows the exact number of atoms of each element in the smallest unit of a substance Multiple of the empirical formula

Practice (1) Identify the following formulas as empirical, molecular, or both. (2) Determine the empirical formula(s) for the molecular formulas identified. NH3, C6H12O6, CH2O, B2H6, H2S

How to determine Molecular formulas Calculate the molar mass of the empirical formula. Determine the multiplier by dividing the molar mass given by the molar mass of the empirical formula (#1) Multiply the subscripts of the empirical formula by the multiplier determined in #2

example The empirical formula of a compound is C2H3O2. If the molar mass of the compound is 118.1 g/mol, what’s the molecular formula?

Formula of a hydrate Hydrates are compounds that have a specific number of water molecules attached to them. Anhydrate is the substance that remains after the water is removed (ionic compound) Example: CuSO45H2O

Naming hydrates CuSO4  5H2O Ionic compound Hydrate Greek prefix Copper(II) sulfate pentahydrate