Acid-Base Titrations: Analysis of Antacid Tablets
Cuenca, Carlo Nicolo B.
Del Prado, Rockson D.
Bachelor of Science in Biology – Major in Medical Biology
College of Science
De La Salle University – Dasmariñas
Dasmariñas, Cavite Philippines
This experiment was performed to learn the technique of acid-base titration and to compare the efficiency of commercially available antacids by looking at their weight of HCl and weight of antacid values. The analysis of antacid tablets was highlighted in this experiment. The efficiency of antacid tablets was determined and compared when the number of grams of HCl can be neutralized by 1 gram of the tablet was found. First, the two antacid tablets (Kremil-S) were crushed and weighed to the nearest 0.01 g which was 0.5003 g and 0.5014g. Then, transferred into a 250 mL flask and added 50.0 ml 0.1M HCl using an acid burette. Then, the antacid was dissolved in the acid. After that, the two drops of phenolphthalein indicator were added and was mixed thoroughly. Lastly, the antacid mixture was titrated with 0.1 M NaOH the solution turned to a faint pink color. Recorded the final volume of NaOH used. Here, two trials were done. After the procedures, the weight of HCl that reacted with 1 gram of antacid tablet was calculated and found the result of 0.31 HCl per gram of antacid tablet. With the recovered amount of HCl, it was found out that the antacid tablet (Kremil-S) that has been tested were not so efficient. The experiment that has been conducted only shows how antacid tablets counteract acidity by reacting with the excess hydrochloric acid in the stomach and its effectiveness as one of the most widely used self-prescribed medicine.
Antacid tablets are probably one of the most widely used self-prescribed medicines. They are taken to relieve the medically underlined conditions of heartburn on acid indigestion and sour stomach. Excessive hydrochloric acid in the stomach causes a feeling of discomfort and a burning sensation beneath the breastbone resulting from a spastic backflow of this acid content into the esophagus.
Antacid tablets counteract acidity by reacting with the excess hydrochloric acid in the stomach. Some tablets contain Al (OH)2 or Mg (OH)2 or both. These components neutralize the excess stomach acids. Antacids are designed to raise the pH level of the stomach from a too-acidic state. Neutral pH is 7, while the normal stomach acid level usually is 2 to 4. Antacids contain sodium, calcium, magnesium or aluminum, or a combination of these. Any of these ingredients can raise pH levels by neutralizing stomach acid.
The efficiency of antacid tablets may be determined and compared by finding the number of grams of HCl that can be neutralized by 1 gram of the tablet. The higher the amount of HCl that can be neutralized by one gram of the tablet, the more efficient is the antacid tablet. In determining the efficiency of an antacid tablet, the volume of unreacted HCl in the antacid mixture is titrated with NaOH. The chemical equation that describes the reaction between HCl and NaOH is
HCl + NaOH→ NaCl + H 2O
The equation to calculate for the amount of HCl neutralized is
MHCl * VHCL = MNaOH * VNaOH
Assuming the density of HCl to be 1g/ml, then the weight of acid that reacts with antacid tablet is equal to the volume of the acid consumed by the antacid tablet. MATERIALS AND METHODS
The two Kremil-S tablets were crushed using mortar and pestle. After, the crushed antacids were weighed to the nearest 0.01 g and transferred it quantitatively into a 250 ml Erlenmeyer flask. Also measured 50.0 0.1 MHCl using an acid burette and added this to the crushed Kremil-S. Dissolved the Kremil-S in the acid as completely as possible and added two drops of phenolphthalein indicator into the mixture and mixed thoroughly. Then, the antacid mixture was titrated with 0.1 M NaOH until the solution...
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