The purpose of this lab is to use gravimetric analysis to obtain the formula of an unknown sulfate sample. Gravimetric analysis is the most accurate quantitative method for determining the amount of an analyte in a sample. This is done by transforming the analye into a water insoluable form which precipitates out of solution and can be isolated by filtration and drying. Then the mass is found. From this mass calculations such as the number of moles, and percent of sufate can be determined. A sample that contains a sulfate of an alkali metal is used in this lab. It is measured and then dissolved in dilute HCl. The sulfate is the isolated by precipitation with barium chloride. The precipitae is collected by filtration and then the mass is measured.