Bicarbonate of soda consists of sodium and hydrogen carbonate.
Bicarbonate of soda is alkaline, and it is often used in recipes for things like cakes and bread.
BBC Good Food explains: “Bicarbonate of soda, or baking soda, is an alkali which is used to raise soda breads and full-flavoured cakes such as gingerbread, fruit cake, chocolate cake and carrot cake.
“It needs an acid (as well as moisture) to activate it so is often combined with cream of tartar, yogurt, buttermilk or milk.
