What is the underlying principle of baking powder?

The underlying principle of baking powder is the release of carbon dioxide gas when it comes into contact with water. This gas causes the baked goods to rise and become fluffy. Baking powder is a dry chemical leavening agent, which means that it does not require any activation from an acidic ingredient like baking soda does. Instead, it contains both an acid and a base that react with each other when mixed with water, releasing carbon dioxide gas. The most common type of baking powder is double-acting, which means that it releases gas twice: once when it is mixed with water and again when it is heated in the oven. This helps to ensure that the baked goods rise evenly and do not collapse.