Many people cannot differentiate between baking powder and baking soda, but these 2 items are not chemically the same.
The reaction of the soda or sodium bicarbonate is that it releases carbon dioxide. When you cook with items like lemon juice, tartar cream, molasses, yoghurt, brown sugar, buttermilk…
This is more potent than the powder and has metallic taste if not neutral. For cup flour add1/4 tsp.
This has cornstarch, tartar cream and baking soda. When we cook, the first leavening is with wet powder and the other when is heated up. Add 1 tsp per flour cup.
Some recipes are better with both these items, and find the best balance because the carbon dioxide from the soda and acids affects the leavening volume.
These items can expire so use them fresh. Get new ones every 3 months and see label for the date,
For this get 3 tbsp white vinegar add ½ tsp baking soda and stir. If there are bubbles, this is good for use.