Experiment 7 Saul Ruiz November 20 2011 Lab 7 Antacid Analysis This experiment is an attempt to determine the concentration of acetic acid in vinegar and to compare the experimental percentage of CaCO3 with the actual mass of the CaCO3 in the tablet which is 500 mg By using the method of titration you are able to determine the percent of acetic acid in vinegar Using the sodium hydroxide in the burette add it to the vinegar combined with the phenolphthalein and stir it until the it reaches the end point which is a faint pink color At this point the moles of CH3COOH are equal to the moles of OH which means that the formula M1V1 M2V2 can be used to solve for molarity and from there moles of a species in the solution CH3COOH aq OH aq H2O aq CH3COO aq The average percent of acetic acid in vinegar obtained from this experiment was about 2 877 On the other hand the average deviation came out to be 0 4 In order to compare the results of 0 3 acetic acid in vinegar we found that the percent error was 4 1 In order to determine the mass of CaCO3 an antacid tablet was dissolved in an acid Afterwards the solution was back titrated with NaOH The NaOH is then added until the solution turns a faint pink color which is considered the end point of the titration At this point the moles of OH are equal to the moles of H by the reaction H OH H2O The amount of NaOH that is used during the titration tells us the amount of calcium carbonate that can be found in each antacid tablet The following reactions show us that this is true CaCO3 s Ca2 aq CO32 aq CO32 aq 2H aq H2CO3 aq HCl aq H aq Cl aq We found that the average mass of CaCO3 in the antacid tablet was 551 mg The average deviation for the mass of CaCO3 was found to be 70 mg The percent error for this was 10 There are various factors that could have contributed to these errors in the experiment For instance one example might have been reading the burette wrong and as a result taking the wrong measurement at some point Another possible error could have originated from the acid droplets on the side of the flask along with some bubbles that may have been present in the burette which may have altered the volumetric measurements For part one the error may have been either overtitrated or undertitrated which would drastically alter the desired results For part two NaOH may have reacted with the air to create carbonic acid Thus this lab focuses both on determining the percent of acetic acid in vinegar and comparing the experimental results to the results given which determines percent error as well as comparing the experimental value of the amount of CaCO3 in an antacid Tums tablet to the given value of 500 mg of CaCO3 in one tablet Titration is used alongside the phenolphthalein in both parts of the experiment in order to perform the experiment and to determine at which point the solution reaches the end point during the titration