Analyt chem -Lab Report 4 - Ly Ngo CHM 3120C Section 001...

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Ly Ngo October 12, 2010 CHM 3120C Section 001 Post Lab 4: Volumetric Determination of Impure Sodium Carbonate (Na2CO3) Introduction The purpose of this experiment is to determine the total amount of carbonate that is actually in a sample. This is done by the method of titration in using standardized HCl to titrate a solution of unrefined sodium carbonate or soda ash. During the process of neutralization, carbonic acid and sodium chloride is produced. Carbonic acid will also decompose to give CO2 and water. This is why during titration that it is important to get the exact amount needed to neutralize the solution in order to give the correct endpoint as well as heat the solution so that carbon dioxide to remove it from the solution. In utilizing the correct titration methods, the percentage of sodium carbonate can be determined to be closely similar to the original amount of sodium carbonate in the unknown (#250). Materials & Methods The students will begin the lab by collecting around 2 grams of dried soda ash, phenolphthalein indication, bromocresol green indicator, one liter of standardized HCL, 200 mL of 6 M HCl solution, and pH paper. The lab begins by obtaining the soda ash from the T.A. and placing it in a dry weighing bottle that will be kept in the dessicator to cool. Then, deionized water and 5-10 mL of standardized HCl solution is going to be rinse the buret with. Next, 3 samples of soda ash is going to be weighed to 0.2 to 0.25 grams and quantitatively transferred into three 250 mL Erlenmeyer flasks. Keep in mind that the samples will be dissolved with 25

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