Larry Cobb said:
Sodium Percarbonate - if full strength, is equivalent to 27.5% Hydrogen Peroxide (90 Volume).
Larry,
It's a tad bit misleading to indicate an equivalent "volume" figure, as you would have no way to use the potential 27.5% in a powder form, "at full strength", so to speak. whereas with liquid hydrogen peroxide, the volume figure is presuming liberation at a particular strength, not the volume of pure 100% hydrogen peroxide. Similarly, the "volume" equivalent of percarbonate should be expressed at potential use concentrations, not the dry powder form in which it is stored. Moreover, when we say that Percarbonate is 27.5%, it is the available oxygen, NOT the percentage of Hydrogen Peroxide by weight. Albeit the error is low by some arguments, as the available oxygen of 100% H2O2 is somewhere around 94%. (edited)
Solvay's Percarbonate FB 400 powder is indeed 27.5% available oxygen,
by weight. However,practically speaking you would need to dissolve it in some sort of aqueous solution first, just as liquid hydrogen peroxide is dissolved in water. FB400 is solubility in water is 120 grams/liter, and it's density is pretty darn close to 1 gram/ml. Presuming you are not actually going to use the product in a concentration that exceeds its solubility in water, at saturation, a liter of Percarbonate & water is going to somewhere nearer 3% available oxygen.