The clear supernatant liquid is filtered y gravity filtration using a vacuum pump. It is dried in an oven and a desiccators and finally weighed. The result obtained is 0. Egg, 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 sulfate in a sulfate solution by using the gravimetric method. Theory: The amount of sulfate is determined quantitatively as barium sulfate, Bases, by gravimetric analysis.
This determination consists of slowly adding a dilute elution of barium chloride to a hot (ICC) unknown sulfate solution slightly acidified with concentrated hydrochloric acid (MM). 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 (Again), used to precipitate halide ions such as chloride ions. Another one would be barium chloride (Abaca), used to precipitate sulfate ions, as shown in this experiment. ABA+ + SASS- Bases (PPTP. ) The white precipitate is filtered, washed with water, dried in the oven (ICC) and weighed as barium sulfate. Advantages: Gravimetric analysis gives a very precise analysis if the methods are followed strictly.
Moreover, it was used to determine the relative atomic masses of many elements to a high degree of accuracy. At the same time, the probability for errors is very low. Also, the equipment required in gravimetric analysis is in expensive. Disadvantages: However, this method only analyzes a single element, or a limited number of elements. As such there are constantly new equipment and technology that allows multiple analyses. The traditional methods have to be followed strictly as one wrong step would give undesirable results, thus giving rise to a need to restart the experiment.
Procedures: (A) Precipitation of Bases 1 . Ml of the given sulfate solution was pipettes and placed into a 250-ml beaker. 2. Ml of water, measured in a measuring cylinder, was added, after which, concentrated HCI was added in the fume hood. 3. The beaker was placed n a heating pan and heated to ICC and ml of barium chloride solution was added drop wise from a measuring cylinder. Vigorous stirring was done at the same time. 4. A watch glass was placed on the beaker to cover it and it was further heated for 20 minutes at the same temperature. 5.
A few drops of barium chloride solution were added to the clear supernatant liquid to test for complete precipitation. (B) Washing and filtration of Bases precipitate 1 . Small pieces of filter paper were placed into the crucible and small amounts of warm water were added to ensure that the filter paper is attached to the base of the crucible. 2. The crucible was attached to a special conical flask (airtight) with an extra hole to be plugged into the vacuum pump. 3. The clear supernatant liquid was slowly poured into the crucible while the conical flask was plugged to the vacuum pump. . To ensure that all the particles were removed from the beaker, a ‘rubber-policeman’ was used and at the same time the beaker was rinsed with warm denizen water. 5. The precipitate was washed a few more times with warm denizen water. 6. Filtrate was then discarded. (C) Drying and weighing of Bases precipitate 1 . The crucible holding the Bases precipitate was placed in the oven at ICC or approximately 30 minutes. 2. It was then removed from the oven and placed in a desiccators for about 10 minutes. 3. After cooled, it was weighed. 4.
The weight of the precipitate is the difference between the weight of the crucible with precipitate and the empty crucible (with filter paper). Discussion: Regarded as one of the oldest methods, gravimetric analysis procedures are usually very accurate but more tedious than other methods. Then again, the only essential equipment needed would be an electronic balance. In any precipitation gravimetric analysis, the species that we are looking for is reacted with a reagent o form a product that is of a known composition, pure, and of a low solubility.
Knowing both the masses of the original sample, as well as the dried product, it is then possible to calculate the percentage mass of the desired species. In this experiment, the sulfate solution is first acidified with hydrochloric acid. This is to prevent the precipitation of barium carbonate (Abaca) and barium hydroxide, Baa(OH)2, as well as to help in forming larger precipitate crystals. Barium chloride is then added quickly to minimize occlusion of foreign ions in the precipitate crystals.