Baking powder and bi-carb soda (also called baking soda) are frequently used in cooking and baking.
Although they look similar you don’t want to use them interchangeably!
Baking Soda is a salt called sodium-bicarbonate. It is used in baking for its leavening (rising) effects as it makes carbon dioxide bubbles when combined with water and an acid (such as lemon juice, vinegar) or heat. Its number in packaged foods is E500. Sounds scary but it is only used as an acidity regulator.
Baking soda is not commonly known as a meat tenderiser but a light sprinkling on meat softens even the chewier cuts. Try it on strips of chicken or beef for that melt in your mouth stir fry. Just remember that a little goes a long way and too much imparts a bitter taste.
Baking powder is a mix of baking soda and a weak acid (normally acid salts). When water is added the chemical reaction above occurs, the gas bubbles causing baked goods to rise. Cornstarch is often included in the mix to stop the chemical reaction occurring during storage.
Check out some more posts about baking and ingredients: