Chem142_Titrate_Prelab

Chem142_Titrate_Prel - UW Department of Chemistry Lab Lectures Online Chem 142 Lab 6 Titrations Standardization of NaOH and Determination of Acetic

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UW Department of Chemistry Lab Lectures Online Chem 142 1 of 3 Lab 6: Titrations Standardization of NaOH and Determination of Acetic Acid Concentration Introduction In the Stoichiometry I lab, the equivalence point of the bleach-hydrogen peroxide reaction was determined by measuring the limiting volume of O 2 (g) produced. In the Fe(II)-phen reaction, the limiting absorbance of the product was measured. In the bleach-peroxide reaction, because the experimental setup did not allow for continuous addition of one reagent to another, we had to make a number of separate runs. In the Fe(II)-phen reaction we were able to make 100 μL additions of Fe(II) to the same solution of phen in a procedure that allowed us greater speed and accuracy. As the Fe(II)-phen reaction indicates, it is possible to make continuous and controlled addition of one reagent to another as long as: (i) the reaction is fast, (ii) the reaction is of fixed stoichiometry, and (iii) there exists a procedure via which the equivalence point can be identified. + 2 n Fe(phen) In this experiment, the equivalence point will be identified by adding an acid/base indicator that changes color over a specific range of pH (acid strength). An efficient way to deliver controlled volumes of one solution or liquid to another is to use a buret in a procedure called a titration . A known volume of titrant is carefully delivered from the buret. As the equivalence point is approached, slow additions are necessary to avoid overshooting the equivalence point. You should be able to identify the endpoint to within a drop (~0.05 mL) or fraction thereof. A carefully designed titration should yield at least 3 significant figures in the volume delivered. Moles of reagent to be titrated. (If a known mass of reagent
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This note was uploaded on 12/03/2008 for the course CHEM 142 taught by Professor Zoller,williamh during the Spring '07 term at University of Washington.

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Chem142_Titrate_Prel - UW Department of Chemistry Lab Lectures Online Chem 142 Lab 6 Titrations Standardization of NaOH and Determination of Acetic

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