Exp 1 Lab Report-1

Exp 1 Lab Report-1 - Buret preparation and calibration and...

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Buret preparation and calibration and cost analysis of antacids using the method of titration Jubilee Ngo Chemistry 100A at University of California, San Diego 9500 Gilman Drive, La Jolla, California 92093 10 July 2006 I. Abstract The method of titration using a buret was used to perform cost analysis of two different brands of antacids. In the first part of the experiment, familiarity with the buret was achieved through its preparation and calibration, which also helped to minimize indeterminate errors. From the calibration, the volume per drop value was determined to be 0.0525 ± 0.0013 mL/drop while the drops per volume was 19.06 ± 0.48 drops/mL In the second part, two brands of antacids, Tums and Longs Acid Relief Antacid Tablets, were titrated twice, first with 1 M HCl and then the excess acid from that titration was titrated with 0.100 M NaOH. The calculated cost per mole of acid neutralized for Tums is $1.93 while the cost per mole of acid neutralized for the Longs Acid Relief Antacid Tablets is $3.05, which significantly higher than Tums. II. Introduction It is estimated that “Americans currently spend close to $1 billion yearly on over-the-counter antacids.” 1 What are the causes of this huge amount of spending? The answer to this question first requires brief knowledge about the digestive system and its pH dependence. The parietal cells on the inner lining of the stomach (called the mucosa) secrete hydrochloric acid (HCl) and help maintain a healthy acidity level of pH 1-2, which is desirable for the digestion of food. “The stomach is [also] lined by a…mucus layer that acts as a barrier and protects the mucosa against the acidic environment, proteolytic enzymes, and mechanical damage.” 2 However, once the pH deviates from this normal level due to overproduction of acid, the defense system is not as effective and problems such as Helicobacter pylori infection can lead to gastric and duodenal ulcers and ultimately, gastric cancer. 2 Hence, substances that can neutralize excess acid in the stomach called antacids are important for this purpose and for solving other health issues such as indigestion and acid stomach. There are several different brands of over-the-counter antacids nowadays, each sold in different quantity and at different prices. Since Americans are spending a considerable amount annually purchasing these products, how can one determine if what we are paying is the right for its effectiveness? Therefore, the purpose of this experiment is to use the method of titration, after careful preparation and calibration of the buret, to perform cost analysis of two of the most popular brands, Tums and Longs Acid Relief Antacid Tablets. Afterwards, a comparison their costs per moles of acid neutralized can help determine which of the two gives the best result for our money’s worth. III. Experimental
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This note was uploaded on 10/16/2009 for the course CHEM CHEM 100A taught by Professor Chem100a during the Summer '09 term at UCSD.

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Exp 1 Lab Report-1 - Buret preparation and calibration and...

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