The reaction between baking powder and an acid is an example of an everyday chemical reaction. As bread bakes, the reaction releases carbon dioxide, which is then trapped in the structure of the cooked dough to make it light and fluffy.
Another example of an everyday chemical reaction is the digestion of food in the stomach. In this case, the acid in the stomach reacts with the proteins, fats and other molecules contained within the food and breaks them down into more manageable parts. Some of these molecules are bonded and dispersed throughout the body via the blood stream, while others go to the intestines where they are fermented by bacteria. Fermentation consists of a series of chemical reactions.
There are two main types of fermentation: lactic acid fermentation and ethanol fermentation. The names refer to the end product, but they both start with the same reactant, glucose. Bacteria consume the glucose and form the by-product. Lactic acid fermentation can also start with lactose, which is found in milk, and is used to create yogurt. This sugar is then broken down in the presence of water to form glucose, another everyday chemical reaction. The bacteria utilize the glucose, excreting lactic acid.