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Acid-Base Titration Chemistry Formal Lab Writeup by A.Mm

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Acid-Base Titration Chemistry Formal Lab Writeup by A.Mm

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  • April 8, 2004
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Abstract

By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the methyl red indicator is more suitable, since it's pH range is closer to the equivalence points of the titrations.

Introduction

Acid-base reactions are one of the most common and important chemical interactions. They are vital to both environmental and industrial systems. As an important variable, pH controls the toxicity, mobility, solubility, and fate of many aquatic ecosystems. Most aquatic life forms cannot survive outside a pH window from about 4.5 to 9. From an industrial viewpoint, manipulation of pH is both a tool for and a prerequisite to all water treatment processes.1 Along with pH indicators, titration is a vital tool in determining the factors of many commercial and environmental systems.

Therefore, knowledge of acid-base titration curves is critical to the environmental scientist. Titration, an analytical technique, allows the quantitative determination of a dissolved substance being titrated, known as an analyte. Titration requires knowledge of the equivalence point: a theoretical point where the chemical equivalents of titrant added are exactly equal to the chemical equivalents of the solute being titrated. It also requires the knowledge of the Endpoint: an operational point which approximates the position...