The pH of Coke products ranges from 2.5 to 4.2. The most acidic Coke product is Coke Classic, which has a pH of 2.5. These beverages contain phosphoric acid, an additive used to enhance the flavor of soft drinks.
In addition to phosphoric acid, Coke products also contain carbonic acid. This forms when carbon dioxide, which makes soft drinks bubbly, reacts in a solution. Bob Peeples, a chemical engineer, says acidic drinks are not dangerous because the stomach already has an acidic environment. The stomach has specialized cells that produce hydrochloric acid, which has a pH of 2.0. This acid is stronger than the phosphoric acid or carbonic acid found in cola products.