Experiment 7

Experiment 7 - EXPERIMENT 7: BUFFER LAB (INFORMAL) Pre-Lab...

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EXPERIMENT 7: BUFFER LAB (INFORMAL) Pre-Lab Questions ( 5 points each ): __10____ / 10 pts Data: ___5__ / 10 pts Table containing pH data from Experiment 1. This table should include the theoretical pH values, the actual measured pH values, and the pH values after correctly preparing the buffer solutions. (5 points) Table containing all pH values for all 7 acetic acid/acetate solutions. (5 points) Sample Calculations: ___5___ / 5 pts Buffer Capacity Calculation (5 points) Results: ___7___ / 16 pts Plots of measured pH vs. Drops (HCl or NaOH) added for each of the 7 buffer solution. Plots must be properly labeled and constructed. Plots must also contain linear regression and the equation of the lines for each. Conclusion: ____3__ / 7 pts _29__ / 48 pts Question 1: 2 pts Question 2: 2 pts Question 3: 5 pts Question 4: 10 pts Question 5: 4 pts Question 6: 5 pts Question 7: 5 pts Question 8: 5 pts Question 9: 10 pts Style (organization, spelling, grammar, neatness, etc…) ____4__ / 4 pts Deductions (i.e., Late Lab Report, incorrect formatting, spelling etc.) - _3____ You need to cite Harris for this one. Total Score ___60___ / 100 pts Experiment 7: Preparation and Investigation of Buffers
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Honor Pledge Results and Calculations Experiment 1 : Comparison of Different Buffer Preparation Procedures In the first part of Experiment 1, 100.mL acetate buffer that has pH of 5.00 that was 2.00M in acetic acid was made from pure liquid acetic acid and pure sodium acetate. The literature values for the pKa and density of liquid acetic acid are 4.756 and 1.049 respectively. From this
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information, the volume of liquid acetic acid and the mass of sodium acetate can be found. The calculations are below. Volume of acetic acid: Mass of sodium acetate: This buffer solution was made and diluted to the 100 mL mark with distilled water; the pH was 4.71. In part two of this experiment, a buffer was prepared by partially neutralizing a weak acid with a strong base. The 100.mL acetate buffer of pH 5.00 that is 0.200 M in acetic acid is to be made with only pure liquid acetic acid and 1.0 M NaOH. In order to find the volume of NaOH to be used the following was calculated: Volume of NaOH Initial moles 0.02 x / / Final moles 0.02-x / x /
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This second buffer solution was also diluted with distilled water. The pH of this solution was 4.46. Lastly, the third part of experiment one was a third and final method to prepare buffers. The calculated value of acetic acid, 1.14mL, was dissolved in a beaker containing about 80.0mL distilled water. A pH electrode was used to monitor the pH as drops of NaOH were added until the pH reached 5.00. The pH of this solution was 5.01. Experiment 2
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This document was uploaded on 11/04/2011 for the course CHEM 241 at UNC.

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Experiment 7 - EXPERIMENT 7: BUFFER LAB (INFORMAL) Pre-Lab...

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