Sodium bisulfite is a type of chemical compound that has a chemical formula of NaHSO3. This is most commonly used as an additive to food and it can be prepared a couple different ways but the most popular and common method is bubbling sulfur dioxide in a solution of sodium carbonate in water. When this chemical is in contact with a chlorine bleach solution, it is going to generate heat. Sodium bisulfite is one of the most weak acids that we have and in terms of some of the specific uses for it, it is used by a lot of home winemakers to help preserve the flavor in the wine and it can be used to help prevent browning when it comes to fruit canning. Lastly, sodium bisulfite is used to be added to the leafy greens in salad bars and other places to help keep their freshness.