Can you use baking powered instead of baking soda?

Yes. If you have alum, cream of tartar or vinegar you can use soda instead of powder.

For alum substitute 2 1/2 tsp soda and 1/2 tsp alum for 1 tbs powder.

For cream of tartar substitute 2 tsp soda and 1 tsp tartar for 1 tbs powder.

mix the above together.

For vinegar put 2 1/2 tsp soda in for the powder, add 1 tsp vinegar with the liquids in the recipe for 1 tbs powder.

Note: baking powder is baking soda mixed with a dry acid that is activated when moistened and heated.