This lab report covers on the employment of gravimetric analysis in the mass determination of chlorine within an unknown chloride solution. In determining the mass percent of chlorine, a pure precipitate containing chloride ions must be prepared. Among the elements that form insoluble chlorides include Pb2+, Hg22+ and Ag+ (Smith and Stanton, 114). This experiment used silver because it is not only easily filtered and readily available, but also undergoes 99.99% conversion from Ag to silver chloride. Chloride ions are made by dissolving chlorine in nitric acid. On the other hand, silver ions are contained within a solution of silver nitrate. Ionic equation for the reaction is written as;In order to improve the percentage conversion and formation of AgCl, appropriate reaction conditions are maintained, which include but not limited to use of excess silver nitrate, and sustenance of temperatures at approximately 95oC. After precipitation of AgCl(s), sufficient washing and filtration procedures are employed to increase the precipitate’s purity before the pure compound is dried and weighed.First, four filter crucibles were cleaned by rinsing with a mixture of 15 ml of deionized water and 6M nitric acid. Subsequently, the four crucibles were dried at 120oC for approximately 2 hours, and their individual mass recorded to 0. The unknown samples were first dried at 120oC for 2 approximately 2 hours and the cooled in desiccators before weighing 0.4 grams of the sample into each dried crucible (Smith and Stanton, 114). Subsequently, each weighed sample was quantitatively transferred into a 400 ml beaker, and the sample in the beaker dissolved with a mixture of 200 ml water and 5 ml of 6 M nitric acid. Upon complete dissolution of the sample, 0.2 M silver nitrate was added into the beakers and stirred until a precipitate began to coagulate. While the temperature was maintained at 95oC for 10 minutes, excess silver nitrate was added into the beaker and continually stirred until formation of the precipitate ceased. The resultant precipitate was carefully decanted into one of the weighed filter crucibles and dried at 110oC for 2 hours. Eventually, the dry precipitate was cooled, weighed, and its mass recorded in the data table (Smith and Stanton, 114). As a means of enhancing precision, four independent trials of the entire process were repeated, and the mass of each pure
Work CitedSmith, Charles and Stanton, Bobby. Experiments in General Chemistry: Gravimetric Analysis of a Chloride, Sulfate or Carbonate Compound. Pittsburg: Cengage Learning, 2009. Print.
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