Determining Phosphoric Acid Content in Soft Drinks.docx -...

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Determining Phosphoric Acid content in soft drinksSamantha Cervantes, Kathryn Bhoorasingh, Janeane Jones, and Anna AndoosAbstract:The purpose of the experiment is to determine the amount of phosphoric acid, H3PO4, in two softdrinks, Pepsi and Coca-Cola, by titrating each sample with sodium hydroxide, NaOH. In order to determine the phosphoric acid content in cola beverages, an acid base titration was used. A standardized sodium hydroxide solution was titrated against a known volume of decarbonated cola to determine the pH, and molarity a standard deviation of the phosphoric acid content. Measures were taken with a pH sensor for Pepsi and Coca-Cola. Four trials were conducted. Twotrials for each and each trial going to a slow and fast titration. It was found that Cola had a much higher concentration of phosphoric acid compared to that of Pepsi.Introduction:Phosphoric acid is a polyprotic acid with the molecular formula H3PO4. It is a colorless odorless crystalline liquid which gives soda it's tangy flavor and prevents the growth of mold andbacteria. Another property of phosphoric acid is that it induces a feeling of thrust. Which is why most soda companies added it to their products. Phosphoric acid is one of several weak acids thatexist in carbonated beverages. It is a component of all cola soft drinks. Phosphoric acid has a much higher concentration than other acids in a container of soft drinks. This can be determined by an acid-base titration. An acid–base titration is a method of quantitative analysis for determining the concentration of an acid or base by exactly neutralizing it with a standard solution of base or acid having known concentration. For the experiment, titrate a sample of cola drink with sodium hydroxide solution and determine the concentration of phosphoric acid, H3PO4. Hydrogen ions from the first dissociation of phosphoric acid react with hydroxide ion from the NaOH in a one-to-one ratio in the overall reactionH3PO4(aq) + OH-(aq) ----> H2O(l) + H2PO4-(aq)The use of a pH sensor will monitor the pH as titration is going on. The region of most rapid pH change will then be used to determine the equivalence point. The volume of NaOH titrant used at the equivalence point will be used to determine the molarity of the H3PO4.

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