It is a rising agent.
The recipe that I use calls for baking soda.
To replace for example 3 teaspoons of baking powder with baking soda, mix 1 teaspoon of baking soda with 2 teaspoons of cream of tartar.
Inasmuch as they are exactly the same thing, absolutely.
The amount of baking soda needed for a recipe will vary depending on the specific recipe. It is best to follow the instructions provided in the recipe you are using for the most accurate measurement.
yes indeed
Baking soda and baking powder are very different in how they work. Think of baking powder as making something more light and fluffy. Baking soda is going to make something taste less sweet and slightly more light. But yes. If your recipe calls for baking soda, or baking powder using the correct amount of both is important. You cannot substitute one for the other.
Baking soda will cause things to rise also. Muffins are smaller so there is not as much need for lift. Baking powder will give more rise than soda. Whoever created the recipe chose to use soda instead of baking powder.
If the recipe calls for it, yes.
Add a teaspoon of baking soda for each cup of sour milk.
The original Nestlés Toll House cookies (chocolate chip cookies) recipe calls for baking soda, not baking powder. There is no substitute for baking soda or baking powder in a recipe. You have to have it.
You can substitute baking soda for baking ammonia in recipes. Use 1/4 teaspoon of baking soda for every 1 teaspoon of baking ammonia called for in the recipe.