This is a chemical reaction that I have seen in my daily life. Vinegar is acidic while baking soda is a base. The 2 mix together to form carbonic acid and sodium acetate from sodium and bicarbonate ions.
It occurred to me not too long ago that I have multiple chemical reactions happen every day when I eat. The chemicals in my saliva break down the food I am eating. The pH in saliva is higher, so it breaks down the carbohydrates in the food I'm eating preparing it to go into my stomach and digest. There are also many reactions that must occur during digestion, such as the stomach acid breaking down the food further.