3 Titration aa

3 Titration aa - Buret pH meter General considerations This...

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Experiment # 3: Titration of an amino acid. Purpose: to identify an unknown amino acid with an acid base titration curve. Reaction Scheme a) an alpha amino acid at pH 7 b) use chemical equations to show an aminoacid protonating and deprotonating at pH values above and below its pka values; c) Calculation the isoelectric point for the aa above Introduction: Use formulas and equations where appropriate. Discuss naturally found aminoacids, write a fisher projection of an aminoacid, discuss acid base properties of amino, carboxy and side chain groups; compare to carboxylic acids (acetic) and small amines (ethanamine); indicate the classification (with formula) of aminoacids into polar, non-polar basic and acidic; define pKa and pIs. Questions: Ch3,8,15,17,18 and 19 Safety NaOH, HCl Dispose all aqueous solutions in the sink. Consumables Kimwipes Standard buffers Common usage Magnetic stirrer
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Unformatted text preview: Buret pH meter General considerations This titration requires the same set up used for buffer titration. The differences are a) a solution of aminoacid will be provided instead of solid b) the NaOH and HCl used for the titration are 0.2 M instead of 1.0M c) You will require to use both acid and base for the titration, make two- 10 mL aliquots; one for acid titration and one for base. Change the buret with a team that is using acid/base to perform the second titration. Procedure 1) Calibrate the pH meter 2) Using a volumetric pipette transfer 10 ml of unknown amino acid solution to a 150 mL beaker. Add approximately 50 ml of water. 3) Titrate the aminoacid with acid or base then change buret and solution to do the second titration. 3) Plot the data as in buffer titration 4) From the amino acids given: Identify the aminoacid and determine the concentration of the unknown solution....
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This note was uploaded on 11/19/2010 for the course BIO 360 taught by Professor Fink during the Spring '10 term at UCLA.

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