06Vinegartitration

06Vinegartitration - H C H O O C 3 Strength of Vinegar by...

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Strength of Vinegar by Strength of Vinegar by Acid-Base Titration Acid-Base Titration 100 points C H 3 O
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The goal is to determine the concentration of acetic acid in vinegar by doing a titration with a solution of NaOH The experiment has two parts 1) You have to determine the concentration of the NaOH solution using a primary standard. 2) You then use the NaOH solution for the Vinegar titration
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? QUESTIONS ? With what accuracy and precision can you determine the concentration of a solution of sodium hydroxide? Using that NaOH solution, with what accuracy and precision can you determine the concentration of a solution of acetic acid by titration?
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Concepts: Strong/Weak Acids Acid Dissociation/K a Concentration Titration Titration curves End point / Equivalence point Indicator Logarithms Mole Relationships a Techniques: Titration pH Measurement Apparatus: Burets pH Meter Primary Standard Primary Standard Weighing by Difference Weighing by Difference Preparing precise solutions Preparing precise solutions Standardization Standardization Volumetric Flask Volumetric Flask Analytical Balance Analytical Balance Pipet Pipet
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The Last exercise involved an acid-base titration in which the concentration of NaOH was given. In this exercise, you will STANDARDIZE the NaOH solution Standardization Analytical determination of the purity or concentration of a substance through reaction with a substance of verified composition and purity ( Primary Standard ) This STANDARDIZATION involves the reaction of NaOH with the PRIMARY STANDARD weak acid, potassium hydrogen phthalate (KHP) O O H O O - K +
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KHP is a monoprotic weak acid. One available proton. [K + ] + H C 8 H 4 O 4 - + OH - C 8 H 4 O 4 = + H 2 O + [K + ] The stoichiometry of the reaction is: Acetic acid, CH 3 COOH , is also a monoprotic weak acid. 1 mol KHP 1 mol NaOH 1 mol CH 3 COOH 1 mol NaOH STOICHIOMETRY STOICHIOMETRY CH 3 COOH + OH - CH 3 COO - + H 2 O It’s pK It’s pK a is 4.7 is 4.7
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The pH at the equivalence point is ~8.5 Phenolphthalein is a reasonable indicator Equivalence Point pH pK a = 4.7 pH ~ 8.5 The titration curve for Acetic Acid with NaOH looks like this. Titration of 50ml of 0.1M Acetic Acid with 0.1 M NaOH
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The pH at the equivalence point in the titration of acetic acid with sodium hydroxide is equal to the pK a of acetic acid. A A = True B B = False
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pH at equivalence point is ~8.5 Equivalence Point pH mL of NaOH added pK a Half titration point pK a = 4.7 pH ~ 8.5
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It does not matter in which order you A.) Standardize NaOH, B.) Titrate Unknown C.) Determine pH of unknown PROCEDURE PROCEDURE A. STANDARDIZATION Prepare solution of known concentration of primary standard, KHP Weigh out sample BY DIFFERENCE * Dissolve fully in
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This note was uploaded on 11/28/2011 for the course CHE 143 taught by Professor Raleigh during the Spring '09 term at SUNY Stony Brook.

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06Vinegartitration - H C H O O C 3 Strength of Vinegar by...

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