Ascorbic Acid (Vit C powder) with Baking Soda = Single Acting Baking Powder? For my gluten free baking, I "have to"* make my own single acting baking powder. I use 2 parts cream of tartar and 1 part baking soda (bicarbonate of soda). It's been fairly successful. 

I would like to know if ascorbic acid powder (pure - just vitamin C - nothing else) could be used in place of the cream of tartar. If so, is the Ascorbic acid stronger? Do I need to change ratio to baking soda? 

(EDITED TO LEAVE OUT UNNECESSARY RAMBLING)

*Why I "have to": 
Baking POWDER - I react to something in commercial baking powder. Maybe the sodium acid pyrophosphate or monocalcium phosphate. So I make my own single acting powder to avoid this problem - and have had no health issues so far with that.

Thanks for your help on this baking powder question!
This answer suggests that you can substitute ascorbic acid for cream of tartar at a 0.75:1 ratio.  However, the answer does not cite how it arrived at that ratio.  It's not an unreasonable idea though, since the pH of ascorbic acid is much lower than that of tartaric acid -- that is, it's more acidic.  I lack the chemistry math to say if the 75% substitution is the right number, though, so you may need to just test it out.