Determining Empirical Formulas from Percentage Composition, Lecture notes of Chemistry

Download Determining Empirical Formulas from Percentage Composition and more Lecture notes Chemistry in PDF only on Docsity! Percentage Composition % composition gives the percentage of each element in a compound by mass. For instance Consider the formula copper (II) oxide CuO. The molar mass of the compound is 63.55 g/mol + 16.00 g/mol = 79.55 g/mol If I have one mole of the compound, that would be equivalent to a mass of 79.55 g (I chose one mole for convenience) The percentage of copper in the sample would be 63.55 g / 79.55 g x 100 = 79.9% The percentage of oxygen in the sample would be 100 - 79.9 = 20.1 % It is possible to work backwards to find the empirical formula of a compound from % by mass information. The following example was taken from the Journal of Chemical Education; Determination of an empirical formula using experimental data Magnesium burns in air to form a compound containing magnesium and oxygen atoms. The following data was collected in an experiment to determine the formula of the compound that is formed when magnesium is burned in air.