Course: CHM 101 (E05N)-NVCC
Professor: Mihaela Chamberlin
Date: 29 April 2017
Experiment Title: Acid-Base Titration
Vinegar is a common household item containing acetic acid as well as some other chemicals. This experiment is designed to determine the molar concentration of acetic acid in a sample of vinegar by titrating it with a standard solution of NaOH.
CH3COOH(aq) + NaOH(aq) -> CH3COONa(aq) + H2O(l)
By adding the sodium hydroxide, which is a basic solution, to the acetic acid, which is an acidic solution, a neutralization reaction occurs. An indicator known as phenolphthalein, is also added to the vinegar. This indicator turns the solution to a dark pink when excess NaOH is added …show more content…
Using a 10-mL graduated cylinder or a 5.0-mL pipet, transfer 5.0-mL of vinegar to a 250-mL Erlenmeyer flask.
Add about 25-mL of distilled water to increasethe volume of the solution for titration. (This will not affect your results)
Add 2-3 drops of the phenolphthalein indicator to the solution in the flask.
Obtained a 50-mL buret and place it in a buret clamp. Using a 250-mL beaker, obtain about 100-ml of 0.1M NaOH solution.
Recorded the Molarity (M) of the NaOH solution, which is 0.187M.
Rinsed the buret with two 5-mL portions of the NaOH solution. Discard the washings.
Observed the markings on the buret. The top is marked 0.0-mL and the bottom 50-mL. Place a small funnel in the top of the buret and slowly pour the NaOH solution into the funnel.
NaOH solution reaches the top line, lift the funnel and allow the solution to fill top line.
Using a small beaker, slowly open the stopcock and drain NaOH solution untilthe meniscus of the NaOH solution is at the 0.00-mL line or below. The buret tip should be full of NaOH solution, and free of bubbles.
Recorded the initial level of NaOh solution in the buret.(Trial 1&2: …show more content…
Even when there was pink color, it often lasted only for a few short seconds until it was swirled away. The actual point of neutralization was a drop before the solution turned pink, but the results from one drop after was close enough. The volume of NaOH that was put into the vinegar was 25.50-mL. The amount of NaOH one drop before that would have been ideal but that did not have a large affect on the data. For this lab, two trials were performed to decide if mistakes were made in the first trial. The completion of two trials completed to help rule out any obvious experimental errors. If mistakes were made in the single trial, the mistakes were not as easily picked up on. I believe the results were generally accurate, although experimental error could have been a factor by inaccurate measurement readings, as well as inaccurate judging of when the pink color was what it was suppose to be. In trial 2 of the experiment, the volume of NaOH that was put into the vinegar was 25.45-mL. The average of the volume in liters was 0.02498-mL. The volume of NaOH in trial #1: 25.50-mL, and trial #2: 25.45-mL at a concentration of 0.1817M. It seemed accurate that the mass of the acetic acid in the vinegar was .2726g. The comparison between those two trials is understandable because there was much more NaOH then vinegar.