Empirical Formula of a Compound Experiment 5
General Chemistry I Lab Wednesday Night
a) The purpose of this experiment involving empirical formulas of a compound is to determine the empirical formula of magnesium oxide and the percent yield in this quantitative experiment1. Even though magnesium, an alkaline earth metal, is the eighth richest metal in the universe and seventh most common element in the crust of the earth, it is not found freely in nature4. Magnesium, when combined with oxygen at elevated temperatures, burns into a bright white flame to produce magnesium oxide4. Also referred to as magnesia, magnesium oxide is the second largest compound found in the earth’s crust. Used in pyrotechnics, flares, and light bulbs, magnesium oxide is also used in the manufacture of insulating materials, refining metals from their ores, and producing medicines4. Magnesium hydroxide, formed when water is added to magnesium oxide during heating, is also known as the laxative milk of magnesium4.
The empirical formula, or simplest formula, is calculated using experimental values, while the element’s symbols and subscripts represent the smallest whole number ratio of atoms in a compound2. Unlike molecular formulas, the empirical formula does not imply the exact number of atoms in a molecule3. After finding the empirical formula, the molecular formula can be determined if the molar mass of the compound is given3. After calculating the empirical formula’s molar mass, molar mass of the compound is divided by the empirical formula’s molar mass to find the ratio between the two formulas. The subscripts in the empirical formula are multiplied by this ratio and the molecular formula results3.
Empirical formulas are calculated using several different methods. The first example is calculating empirical formulas from percent compositions using the percents of the different elements. Empirical...