What does bicarb do to pancakes?

Baking soda (sodium bicarbonate), also called bicarb, is a common leavening agent used in cooking and baking. When baking soda is combined with an acidic ingredient such as buttermilk, yogurt, or lemon juice, it undergoes a chemical reaction that releases carbon dioxide gas. This gas causes the batter or dough to expand, resulting in a lighter and fluffier texture.

In pancakes, baking soda is used as a leavening agent to help them rise and become fluffy. When the baking soda is mixed with the buttermilk, a reaction occurs that produces carbon dioxide gas. The carbon dioxide bubbles up and causes the pancakes to rise. The pancakes also get some of their flavor from the baking soda.