2. Sodium bicarbonate is an inorganic salt, a white crystalline powder, odorless, alkaline and soluble in water. It slowly decomposes in humid air or hot air to produce carbon dioxide, which is completely decomposed when heated to 270℃. In case of acid, it will decompose strongly to produce carbon dioxide. Sodium ion is normal to human body, and it is generally considered to be non-toxic. But excessive intake may cause alkalosis. Solid sodium bicarbonate gradually decomposes above 50℃ to generate sodium carbonate, water and carbon dioxide gas, which is often used as a leavening agent for making biscuits, cakes, steamed bread and bread. Sodium bicarbonate is still sodium carbonate after the action, and excessive use will make the finished product have an alkaline taste.