Baking powder is a chemical leavening agent, meaning it helps baked goods rise. It's a mixture of:

* Sodium bicarbonate (baking soda): This is the main ingredient that releases carbon dioxide gas during baking.

* One or more acids: These react with the baking soda to produce the carbon dioxide gas. Common acids include cream of tartar, monocalcium phosphate, and sodium aluminum sulfate.

* A drying agent: This prevents the ingredients from clumping together. Starch is often used.

Here's how baking powder works:

1. When you add water to baking powder, the acid and baking soda react, releasing carbon dioxide gas.

2. This gas gets trapped in the batter, causing the baked goods to rise.

Baking powder vs. Baking soda:

* Baking soda needs an acidic ingredient (like buttermilk, yogurt, or lemon juice) to activate.

* Baking powder already contains an acid, so it doesn't require additional acidic ingredients to work.

Types of baking powder:

There are two main types of baking powder:

* Single-acting baking powder: It releases all its carbon dioxide when exposed to moisture.

* Double-acting baking powder: It releases some carbon dioxide when it comes in contact with moisture and releases the rest when heated in the oven. This gives the batter a second rise for better texture.

Storing baking powder:

Baking powder loses its potency over time. Store it in a cool, dry place and replace it every 6-12 months.