Final answer:
The process of an antacid tablet reacting in water is a rapid chemical reaction characterized by the release of gas. This occurs when components like calcium carbonate in the antacid neutralize stomach acid, producing calcium chloride, water, and carbon dioxide gas.
Step-by-step explanation:
When an antacid tablet is placed in water, the best description of the process is a rapid chemical reaction where gas is released. Antacid tablets typically contain Arrhenius bases like Al(OH)3, Mg(OH)2, CaCO3, and NaHCO3 that react with and neutralize stomach acid. For example, calcium carbonate reacts with hydrochloric acid in the stomach to produce calcium chloride, water, and carbon dioxide gas, leading to a reduction in acid and sometimes a belch from the released CO2.
CaCO3(s) + 2HCl(aq) = CaCl2(aq) + H2O(l) + CO2(g)
This reaction is an example of a neutralization reaction, which is a type of acid-base reaction, and in the case of antacids, it typically happens rapidly upon the dissolution and reaction of the antacid in the stomach's hydrochloric acid.