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Experiment 20pH Titration: Phosphoric Acid in ColaDrinksStacy JungDavid YapMarch 2, 2016CHEM 1212KSection A23TA: Anthony Lloyd IIHonor Pledge – Freshman Chemistry LaboratoriesI did not copy any portion of this work from the work of other students,old lab reports, or unreferenced materials. I understand that such activityis a violation of the Georgia Tech Honor Code.______________________________________Signature
IntroductionA titration involves the addition of a solution, called the titrant from a buret to a flask containing a sample called the analyte. The titrant and analyte are acids or bases. At the equivalence point, the amount of acid or base added as titrant is equal to the amount of acid or base initially present in the analyte. In other words, at this point, the moles of acid equals the moles of base. The purpose of acid-base titrations is to find the amount of a known acidic or basic substance through acid-base reactions. The analyte is the solution with an unknown molarity, which can be determined by titrating it with a volume of titrant of known concentrationrequired to neutralize it. With this information, the equivalence point can be found. In this experiment, the concentration of phosphoric acid in commercial colas was determined using an acid-base titration. The acidity constants for phosphoric acid was determined by monitoring the pH change of the solution throughout the titration. The titration of phosphoric acid was carried out using a sodium hydroxide solution whose concentration was determined via titration with acid using a visual indicator.Strong acids are completely ionized in aqueous solution whereas weak acids are only partially ionized in aqueous solution. The acid neutralization reaction for a weak acid titrated by a strong base is . As base A is added, the concentration of HA decreases and the concentration of A- increases. A titration curve can be plotted by recording the pH as base is added. The equivalence point of monoprotic acid is where weak acid has just been neutralized by the base, and the number of moles of acid in the original sample is equal to the number of moles of base added. The amount of weak acid in the initial sample can be calculated using the volume of base