This is a leavener (something that causes to dough to rise). It is composed of a basic (high pH) powder. When it reacts with water and an acid added to the dough (like buttermilk, lemon, etc) then a reaction occurs that creates gas. Baking powder is baking soda with an acid already in the powder, so no additional acids need to be added to the dough to create a reaction. Only liquid is required.
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