A cross section of a Mad-Dawg gumball shows an outer layer of citric acid and malonic acid, beneath that a layer of food coloring, sugar, and flavoring, beneath that a layer of sodium bicarbonate (NaHCO₃), and finally in the middle-gum! A 12-year-old puts one in his mouth and immediately puckers, smiles, and then foams at the mouth before chewing. Where did the foam come from?

Question

Quizplus · Accepted Answer

When citric acid and malonic acid react with sodium bicarbonate, it produces an unstable carbonic acid, which then breaks down into water and carbon dioxide gas. The release of carbon dioxide gas creates the foam.

A Cross Section of a Mad-Dawg Gumball Shows an Outer