Lab Report

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Lab Report

Lab Report


This science fair project was performed to find out what conditions will make tablets dissolve faster. The experiment involved using Alka-Seltzer antacid tablets, water and hydrochloric acid at different temperatures. Alka-seltzer original effervescent tablets contain three active ingredients, aspirin, sodium hydrogen carbonate and citric acid.

Aspirin belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking the action of a substance in the body called cyclo-oxygenase. Cyclo-oxygenase is involved in the production of various chemicals in the body, some of which are known as prostaglandins. Prostaglandins are produced in response to injury or certain diseases and would otherwise go on to cause pain, swelling and inflammation. Aspirin is therefore used to relieve pain and inflammation. Sodium hydrogen carbonate and citric acid form antacids by their effervescent reaction with water. They decrease the acidity of the stomach's juices, by binding to and neutralising excess acid. This helps to relieve the symptoms of heartburn and indigestion and settles the stomach. The combination of these medicines is used primarily to relieve headaches accompanied by an upset stomach, which can ofter occur after over-indulgence in food, drink or both. It can also be used to relieve various other types of aches and pains.

The original Alka-Seltzer was invented in 1931, the active ingredients are: 325 mg of Aspirin, 1000mg of Citric Acid and 1916mg of Sodium Bicarbonate, designed to treat pain and simultaneously neutralize excess stomach acid. It is provided in the form of large effervescent tablets, which are dissolved in a glass of water. As the tablets dissolve, the base (bicarbonate) and the acid (citric acid) react vigorously producing carbon dioxide gas, which also produces enough agitation to allow the active ingredients to dissolve slowly.


The Alka-Seltzer antacid tablet will dissolve most quickly in a hydrochloric acid solution and at the highest temperature.

Overview of the Experiment

Alka-Seltzer is an antacid medication used for relief of heartburn and neutralizing stomach acid. The pH level in our stomach is normally between 2 to 3. The food that we eat will enter the stomach where acid is then secreted to help in its digestion. When too much food is eaten, even more acid is produced. At times, the pH level falls below 2. This is the cause of the heartburn. Alka-Seltzer tablets consist of aspirin, sodium bicarbonate and citric acid. As an antacid the tablet will provide quick pain relief ...
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