When adding baking powder to an expired cake mix do you need add soda as well?

No, you generally don't need to add baking soda to an expired cake mix if it already contains baking powder. Here's why:

* Expired Baking Powder: Baking powder is a combination of baking soda, an acid, and a drying agent. Over time, the acid component can lose its potency, making the baking powder less effective.

* Baking Soda's Role: Baking soda requires an acid to activate and create bubbles that make cakes rise. Cake mixes typically have an acid component already built in.

What to do:

1. Check the Baking Powder: If the baking powder in your mix is definitely expired (check the date), it's best to use fresh baking powder.

2. Use a Little More: To compensate for possibly weakened baking powder, you might want to add a tiny bit more fresh baking powder (maybe 1/4 teaspoon) to the mix.

3. Taste Test: If you're unsure, it's always a good idea to make a small test batch first to see if the cake rises properly.

Remember: Adding baking soda to a cake mix that already contains baking powder can make the cake taste soapy or have an unpleasant flavor.