Titration Lab Essay

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Finding the Concentration of Citric Acid in Orange Juice I. Introduction The purpose of this experiment was to find the concentration of the citric acid in orange juice. It was assumed that 100% of the juice was citric acid and it was disregarded the other possible acids within the juice, rendering them insignificant to the overall concentration of the acidity in the orange juice. For that to be achieved, the potassium hydrogen phthalate solution had to be made of 0.1M. Then, sodium hydroxide would have to be titrated against the potassium hydrogen phthalate to standardize sodium hydroxide to 0.1M as well. Titration is the procedure used to determine the concentration of some substance by the controlled addition of a solution into a reaction vessel (flask) from a burette. By using titration, the volume of the solution delivered from the burette may be determined very precisely. This reliable primary standard solution became useful as a titration was made against the orange juice to find the molarity of the citric acid. The indicator Phenolphthalein was the substance used to signal when the titration reached the point at which the reactants are stoichiometrically equal as defined by the balance reaction equation. Phenolphthalein is a chemical compound with the formula C₂₀H₁₄O₄ and is often written as "HIn" or "phph" in shorthand notation. Often used in titrations, it turns colorless in acidic solutions and pink in basic solutions. Sodium hydroxide or Hydrochloric acid would not have been as effective or accurate because they would have reacted with the water vapor from the air. In this lab setup, graduated cylinders or beakers were not used. Instead, a burette and a pipette were used because they were the most accurate pieces of equipment that were available. The equipment needed to measure very accurately because precise measurements were needed to find

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