Acidification

The video shows how sulfur acidifies water when sulfur is burned, forming sulfur oxides that then combine with water in the atmosphere, creating sulfuric acid, which is a strong acid. In the second clip, I use carbon dioxide from exhaled air to acidify the water. Carbonic acid is formed, which is a weak acid. BTB has been used as an indicator; BTB turns yellow in acidic solutions. If you want to learn more about acidification, read the book Chemistry 7 in Apple Books by Kaj Schmidt