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Lab Report

By | June 2011
Page 1 of 3
Name: Tan Zuen Rian
Admin No.: 1155592
Class: 1A/02
Experiment 4:
Quantitative Determination of Sulphate by Gravimetric Analysis

Synopsis:
This experiment aims to determine the amount of SO42- via the gravimetric method. By this way, we will be able to familiarize ourselves with the procedures of gravimetric analysis. Precipitation of BaSO4 is done by acidifying the diluted sulphate solution and then adding BaCl2 solution after heating it for some time. A test for complete precipitation is done by adding a few drops of BaCl2 solution after digesting the solution for 20 minutes. The clear supernatant liquid is filtered by gravity filtration using a vacuum pump. It is dried in an oven and a desiccator and finally weighed. The result obtained is 0.2005g, which is more than expected, thus proving the presence of impurities in the precipitate. Thus, measures have to be taken to ensure a lower concentration of impurities. Objective:

The objective of this experiment is to determine the amount of sulphate in a sulphate solution by using the gravimetric method.

Theory:
The amount of sulphate is determined quantitatively as barium sulphate, BaSO4, by gravimetric analysis. This determination consists of slowly adding a dilute solution of barium chloride to a hot (250oC) unknown sulphate solution slightly acidified with concentrated hydrochloric acid (12M). The method used here is gravimetric analysis. It is a method based on isolating a substance required, either in pure form or in a combined form from a sample. Once the substance is isolated successfully, it is then weighed. It is known that solubility differs for all compounds. As such, there are compounds that are practically insoluble. As such, precipitation is used. Two of the common inorganic precipitating agents are silver nitrate (AgNO3), used to precipitate halide ions such as chloride ions. Another one would be barium chloride (BaCl2), used to precipitate sulphate ions, as shown in this experiment....
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