The ingredients sound right. I would GUESS this is a slightly stronger mixture than commercial baking powder. As a rule of thumb, baking powder is 1/4 the potency of baking soda, suggesting that soda is about 1/4 of the mixture that is baking powder. Your recipe has the soda at about 36% by weight, making it a little more potent but not twice the strength.
If you want to use this recipe, I suggest a side by side comparison test.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan