prelab1 - Pre-lab Experiment 1 Aspirin Titration 10.16.06...

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Pre-lab Experiment 1 Aspirin Titration 10.16.06 Back titration is a method to titrate an unknown solution that may have a slow reaction that can affect the end point accuracy when titrating. The process involves reacting a known amount of a known concentration of base, letting the reaction fully take place, then “back” titrating with a measured amount of a known concentration of acid to neutralize the amount of excess base added, thereby determining the amount of base needed to fully react with the sample and allowing you to calculate the molarity and concentration of the unknown substance being titrated. Equations : Aspirin reacts with Sodium hydroxide in the following way: C 9 H 8 O 4 + 3NaOH ---------> C 9 H 5 O 4 - + 3H 2 O + 3Na + And hydrochloric acid reacts with sodium hydroxide in this manner: 7C 9 H 7 O 4 - + NaOH ---------> C 7 H 5 O 3 - + H 2 O + Na + Procedure : First, 250 mL of a 0.1M solution of HCl must be made from a stock solution with a density of 1.188g/ mL that is 37% wt. To obtain the volume of concentrated HCl needed to dilute up to the 250 mL mark
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This note was uploaded on 04/27/2008 for the course CHEM 208 taught by Professor Poe during the Spring '07 term at University of Louisville.

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