[pantone159]

I am looking for a recommended procedure for making ferric ammonium sulfate solutions.
My CRC has a recipe for ferrous ammonium sulfate, namely 0.5 M with 10 ml of conc H2SO4 per liter.
The ferrous sulfate recipe is similar, 0.5 M with 10 ml acid.
The recipe for ferric sulfate is 0.25 M, but ths time with 100 ml of conc H2SO4 per liter.

There is no specified recipe for ferric ammonium sulfate.  I am hoping that I don't need so much acid in this case, as the alum dissolves easier than the plain sulfate.