The purpose of this experiment was to determine the percent of sulfate ion in an unknown sample through the process of digestion. Each person in the lab section did the experiment and gained a percent of the sulfate ion. Then statistics was used to compare final percents gained by the class compared to the actual percent sulfate ion in the experiment and errors in the experiment were determined.
Introduction.
In chemistry there are different ways of figuring out what and how much of a certain substance there is in a mixture. In this experiment the main goal was to figure out how much sulfate was in a mixture, and then beyond that determining the percent of error for the experiment. One way of determining how much of a substance is present is through the gravimetric analysis which is a form of quantitative analysis which deals with how much of a substance there is the compound. There are several steps to this procedure. The first of these is to make sure that the sample dry so that there is no added mass from extra water molecules in the sample. The sample is considered dry when it consistently weighs the same thing after repeated heating in an oven at about 110 degrees Celsius. This will give the original mass of the sample. Then the sample is dissolved in deionized water and a small amount of acid is generally added to prevent precipitates from forming. If the sample doesn't dissolve in water it is then dissolved in an acid solution. "Precipitation reactions are processes in which soluble reactants yield an insoluble solid product that drops out of solution." Then a reagent is added to yield a precipitate of known chemical composition so that of the compound being analyzed is used up in the solution and there is excess of the reagent being added. The next step is digestion this is actually making the new compounds crystals larger by heating the compound just below the boiling point for some amount of time.