# 9 - Titration Lab Report Wenting Guo Purpose A series of...

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Titration Lab Report Wenting Guo 10/9/08 Purpose: A series of titration experiments will be conducted to precisely determine the concentration of a strong acid, Hydrochloric Acid (HCl.). By performing this quantitative experiment precisely, titration technique is used because, by doing titration, the amount (in moles) and volume (in ml) of the acid will be accurately measured. Thus, the concentration will be precisely measured. Method: Since the moles of monoprotic acid are equal to the moles of base (TRIS) in a neutral solution, so titration will be used to determine the moles of an acid by adding a base. In this experiment, students titrate to determine precisely the quantity of hydrochloric acid by measuring how much it take a weak base (TRIS, tris-(hydroxymenthyl) aminomethane.) to neutralize the solution. To visually see the end this titration, an acid-base indicator, Bromocresol green (BCG), will be added to the solution to show when a neural solution is formed. BCG gives a neutral solution a green color since it changes from blue in basic solutions to yellow in acidic solutions. The weak base is used as a primary standard since it is a solid that can be obtained in high purity. By weighting accurately the mass of the base in a weighting boat on a digital balances , the moles of the base in the solution will be calculated according to equation (1) Mol=mass/molar mass . The volume of the acid used is precisely recorded. As moles of acid added from the buret equals the moles of base in a neutral solution in a Erlenmeyer flask, the moles of acid will be precisely/acurately determined. The volume of the adding acid can be precisely determined since buret of a titration apparatus is calibrated to 0.1 ml, and the stopper will enable we control the adding solution drop by drop when it is close to the equivalence point. As we measure the mass and the volume, the concentration of the acidic solution can be determined from calculation. Proper use of equipment leads to a precise result. There are a few instruments used in this

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## This note was uploaded on 05/09/2010 for the course BIO biology taught by Professor Meighan during the Spring '09 term at Berkeley.

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9 - Titration Lab Report Wenting Guo Purpose A series of...

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