It is a process where an acid reacts with an alkali to produce salt and water. Sodium bicarbonate is a white solid that dissolves in water to form an alkali. It can also react with acids like hydrochloric acid to produce salt, carbon dioxide, and water. Some examples of acid-base reactions include using sodium bicarbonate to relieve indigestion by neutralizing stomach acid, in baking powders to produce carbon dioxide and lighten cakes, and in fire extinguishers where it reacts with acid to produce carbon dioxide to put out fires.