Batters

• An experienced baker whisks or sifts dry ingredients together before adding baking powder to the mixture. He creates a chemical reaction by adding the baking powder as the final dry ingredient and then stirring in the recipe's liquids, according to website Science Buddies. Baking powder interacts with the fluids to create carbon dioxide gas, producing bubbles that act as leavening agents. Some brands of baking powder are called single-acting, because most of the fizzy chemical reaction is confined to the batter.

Heat

• Double-acting baking powder packs an extra punch by releasing bubbles both in the batter bowl and in the oven. A chemical reaction occurs when baking powder's acidic compounds -- usually cream of tartar and sodium aluminum sulfate -- respond to the sodium bicarbonate component. This generates more air pockets, which find support in the proteins in the eggs and flour -- forcing the bread or muffin to rise, according to Science Buddies.

Leavening

• For speed of leavening, baking powder outperforms yeast. Standard bread recipes rely on yeasts, which are single-cell organisms that generate carbon dioxide when they interact with carbohydrates in the dough, according to Science Buddies. The drawback to using yeast is the time required for dough to rise -- often, several hours. With baking powder, rising occurs more rapidly; because of this, baked items made with baking powder are known as quick breads.

Freshness

• Baking powder loses its effectiveness when it comes into contact with moisture. Baking powder from a freshly opened container maintains its effectiveness, on average, for 3 to 6 months, according to OChef.com. Dampness reduces baking powder's leavening abilities. Seasoned bakers store their canisters in dry places and avoid dipping wet measuring spoons into the baking powder. Test your baking powder by pouring 1/3 cup into some hot water and watch for bubbles, which indicate that the batch is still good.