Experiment 2-pH Titrations of Weak and Strong Acids

Experiment 2-pH Titrations of Weak and Strong Acids -...

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Laboratory Report Form for Chem 207L Expt. 2 – pH Titrations of Weak and Strong Acids Analytical Chemistry Laboratory – Fall 2010 Name: _ Kelley Krueger ____________ Name: __ Krista Hawley ___________ __ Name: __ Brittany Adams ___________ Date(s) of Experiment: _ September 14 and 21, 2010 _ Objectives: 1. To carry out replicate titrations on a strong acid (hydrochloric acid, HCl) and a weak acid (acetic acid, HOAc) to a visual end-point using phenolphthalein as the indicator. 2. To develop titration curves for the titration of the same acids using a pH meter. Compare the end points obtained from the pH meter vs. the indicator for each acid. 3. From the titration experiments determine the initial concentrations of each of these acids. 4. Determine the K a of HOAc using the Henderson-Hasselbalch equation. 5. Identify the type of acid (HCl or HOAc) and the concentration of an unknown acid sample. Balanced Chemical Equations: KHP + NaOH KNaP + H 2 O HCl + NaOH NaCl + H 2 O HOAc + NaOH NaOAc + H 2 O Where OAc = CH 3 C(O)-O Data: Standardization of NaOH Solution (2 pts.): Replicate No. #1 #2 #3 #4 Wt. of KHP 0.5579 g 0.5756 g 0.5315 g 0.5581 g ml of NaOH Used 27.40 mL 28.10 mL 25.85 mL 26.95 mL Standardization of HCl Solution - Visual (2 pts.): Replicate No. #1 #2 #3 [ P a g e | 1]
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HCl Aliquot, ml 25.00 mL 25.00 mL 25.00 mL ml of NaOH Used 24.74 mL 24.65 mL 25.60 mL Standardization of HOAc Solution - Visual (2 pts.): Replicate No. #1 #2 #3 HOAc Aliquot, ml 25.00 mL 25.00 mL 25.00 mL ml of NaOH Used 24.61 mL 23.90 mL 25.05 mL pH Meter Titration of HCl: List data (pH vs. ml NaOH added) on back of this sheet or on an extra sheet. (2 pts.) pH Meter Titration of HOAc: List data (pH vs. ml NaOH added) on back of this sheet or on an extra sheet. (2 pts.) Titration of Unknown Acid (2 pts.): Unknown B Replicate No. #1 #2 #3 #4 Unknown Aliquot, ml 10.00 mL 10.00 mL 10.00 mL N/A ml of NaOH Used 10.72 mL 10.74 mL 10.71 mL N/A pH of Unknown Acid (1 pt.) - ___ 2.92 ____ Calculations: Standardization of NaOH Titration 1: 0.5579 g KHP = 0.002731 mol = 0.09967 M 204.23 g KHP/mol KHP 0.02740 L Titration 2:
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This note was uploaded on 11/21/2010 for the course CHEM 0227 taught by Professor Korir during the Fall '10 term at Drury.

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Experiment 2-pH Titrations of Weak and Strong Acids -...

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