IB Chem HL Internal Assessment To what extent does the mass of an antacid affect its ability to neutralize the stomach’s pH level? Introduction Acid indigestion, more commonly known by the term “heartburn” is a stomach problem caused by the regurgitation of gastric (stomach) acid. Gastric acid is a fluid found in our digestive system, normally with a pH of around 2.0 (highly acidic on the pH scale), as it is primarily composed of HCl, KCl and NaCl and contributes to the breaking down of all the foods we digest. Heartburn results in a painful burning feeling in the chest and its duration can vary from person to person. Other symptoms include feeling as if there is food stuck in the throat and/or a burning feeling in the pharynx. I chose to examine the pH levels of a few store-bought antacids in relation to a home remedy, in order to determine which of the two types are more effective in the neutralization of gastric acid as it undergoes heartburn, whilst evaluating the mass of each antacid. Antacids usually come in the form of a tablet/pill and are taken to help neutralize stomach acid and reduce symptoms of heartburn, as they are composed of weak bases, such as calcium carbonate or certain hydroxides, for example. Once I was satisfied with my topic, I was able to derive my research question; To what extent does the mass of an antacid affect its ability to neutralize the stomach’s pH level? The neutralization process focuses on the reaction of an acid and a base, resulting in the formation of a salt and water. The reaction would look something like this; HCl + XOH → XCl + H2O When the basic reactant, NaOH, is dissolved in water, it becomes an alkali. The products are a result of the acid and base reacting, forming water as the H+ and OH– react. The second product formed is a salt, NaCl, in this case, as the sodium (Na) and the chlorine (Cl) ions reacted. The independent variable in this investigation is the mass of the antacids, because I can choose the mass of TUMS tablets and baking soda I use in the experiment, whilst the dependent variable is the change in pH levels of the antacids; the number of acid drops required to neutralize the solution. This is measured by counting the amount of acid dropped from the burette. Also, I controlled the temperature to be constant because that might have affected the final rate of reaction and as a result, altered my data. The constant, or controlled variable, was the amount of HCl used. Materials: · Safety goggles · Store-bought antacid (TUMS) · Baking Soda · Mortar & pestle · Hydrochloric acid · Balance · Distilled water · 6 different 100mL beakers · Flask · Universal pH indicators · pH buffer solutions · 50mL graduated cylinder · Burette · pH meter Procedure: 1. Safety goggles were used throughout the entire experiment for safety precautions. 2. TUMS antacid tablet was crushed into a fine powder using the mortar and pestle. 3. The mass of the two antacids were record.