The pH of the acid in the stomach is 2. When a person has heartburn, the acid in their stomach is coming up the esophagus (lower throat) and burning the lining of the esophagus.

Why would a person take an Alka Seltzer tablet for heartburn?

Alka Seltzer tablet contains "Calcium carbonate" that reduces the amount of acid in the stomach. Thus a person is preferred to take Alka seltzer for heartburn.

Explanation:

Heartburn is a problem created by acid reflux and it causes pain in the lower part of the stomach. It affects the food pipe that carries food to the stomach.

Symptoms of heartburn can cause a salty taste of fluid in the throat region and it causes burning pain in the breast bone. Antacids are generally preferred for the treatment of acid reflux as it reduces the acidity and amount of acid content in the stomach.

Alka-Seltzer is the most common tablet preferred for heartburn problems. This tablet dilutes the acid content and thereby reduces the pain in the stomach.