Acetic Acid Concentration

ABSTRACT

The experiment aims to find the concentration of acetic acid in the vinegar sample by titrating it to a standardized NaOH solution, a base solution. A standardized 0.100 M NaOH solution was prepared from an available concentration of NaOH specifically a 1.00 M NaOH. The volume of the standardized solution (titrant) used which is 0.100 L was calculated using the M 1 V 1 = M 2 V 2 relationship. It was then gradually added to the vinegar solution until the acid-base reaction was completely neutralized. To regulate the reaction, phenolphthalein, an acid-base indicator, was added beforehand to the vinegar (analyte). The indicator will change its color, signaling that the end point is obtained and the volume of NaOH used can now be

Titration is an analytical method used in the laboratory to determine the concentration of an unknown solution using a solution of accurately known concentration referred as the standard solution. Since the volumes of both solutions and the concentration of the standard solution are clearly identified, it is possible to calculate the concentration of unknown solution. The standard solution is gradually added to the unknown solution until the equivalence point, a point at which the moles of an acid is equivalent to the moles of the base, is attained. (Chang,

The process reaches an endpoint when the two solutions completely and exactly neutralized each other. However, in determining the neutralization time by speculating the change in color, one must be critical and careful enough to get accurate and precise data. In conducting this experiment, some possible errors affect the accuracy of the data. The first possible source of error encountered is in the miscalculation in preparing the titrant. Excess or lesser amounts of 1.00 M NaOH can lead to inappropriate standardization. Consequently, an incorrect standard solution prepared yielded to the wrong number of moles of NaOH which consequently give us wrong data. Another issue arose with the amount of the indicator used. Since drops are the measurement associated with the amount of phenolphthalein, it is quite difficult to obtain an accurate amount. A slight error in the indicator can shift the endpoint and consequently affects the volume of the obtained NaOH. Lastly, the final source of error of this experiment is misjudging the color of the indicator near the endpoint. The color change is very intricate that even a small amount of the standard solution can produce different shades of the color. With these uncertainties, a 23.3 % error was committed given that the theoretical molar concentration of acetic acid in the the vinegar sample is