Acid Base Titration

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July 29, 2011 Title: This report highlights an experiment involved with Acid-Base Titration. Introduction: According to the Arrhenius theory an acid can be defined as a substance that dissolves in water and produces hydrogen ions (H+), while a base produces hydroxide ions (OH-). The Bronsted-Lowry theory states that all acids are proton donors and all bases are proton acceptors. A neutralization reaction occurs when protons (H+) from an acid combine with hydroxide ions (OH-) from the base to produce salt and water. For instance, the neutralization of HCl by NaOH is written as: HCI + NaOH -----------> NaCl + HOH Equations for neutralization reaction are balanced so that the amount of H+ will be equal to the amount of OH-. The addition of a specific amount of base required to neutralize an acid in a sample involves a titration. An indicator in a sample will change color when all the H+ from an acid has been neutralized. The addition of a base should be stopped when the indicator changes color which therefore determines the endpoint. At this point the volume of base used to neutralized the acid can be determined. Phenolphthalein is the indicator which is colorless in an acid but changes to a faint and permanent pink color in base. The purpose of this experiment is to prepare a sample for titration with a base, become familiar with a buret while using proper titration technique in reaching an end point. Hypothesis : If I titrate a base of known concentration with an acid of unknown concentration then I can determine the concentration can be calculated because of the titration calculation. Materials : • Vinegar • Two small beakers (150mL) • 250-mL Erlenmeyer flask • 10-mL graduated cylinder • 50-mL buret • Buret clamp • Small funnel • M NaOH Hazards : • Chemical spill • Broken glass
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