What Makes an Antacid Tablet Dissolve?

Antacid tablets dissolve through ionic dissociation in polar solvents such as water and stomach acid. The resulting alkaline ions react with stomach acid, neutralizing it.

The components of antacid tablets include aspirin, sodium bicarbonate and citric acid. As they dissolve and neutralize stomach acids, they raise pH level in the stomach to between 3 and 4 providing rapid pain relief from gastric reflux. The higher the temperature of the polar solvent, the higher the chemical activity of the reaction, and consequently, the more rapidly the antacid tablet dissolves. A more acidic solvent has a larger concentration of free hydrogen ions that readily react with the basic ions from tablet dissolution. This abundance of hydrogen ions makes it easier for the basic ions to participate in a neutralization reaction, accelerating the reaction rate.

Antacid tablets can be used in a stoichiometric calculation of the number of moles in an acidic solution. The number of moles of each of the basic components of an antacid tablet must be known. The tablets are ground up and weighed. The number of moles of the different basic salts in a certain amount of ground-up powder is calculated using a simple proportionality formula. An acidic solution is then titrated onto the tablets until complete neutralization, where no visible fizzing occurs. The volume of the acidic solution used can be used to calculate its acidity.