How can I dissolve a precipitate when stuck to the side of a boiling flask I’ve been experimenting with producing Iron Acetates and I’ve run into a snag. Here’s my process so far:


  I started by adding white vinegar and ~50% Hydrogen Peroxide to a reaction vessel with steel wool sponges and allowing it to react for a month. After that I ran the solution through a filter multiple times until it was fairly clear to remove most of the unreacted solids. After that I tested an aliquot of the fluid by placing some leather in it to see if the leather turned black. It did quite quickly. After that I placed it in a boiling flask and heated it with a flame directly (because I don’t have a big enough beaker or other apparatus to indirectly heat it) and it turned orange. I’m guessing this happened because the elevated temperature allowed it to react with atmospheric oxygen. I continued heating till the solvent was gone leaving a red-brown-black solid on the side of the boiling flask.




I want to dissolve the solid so I added ~100mL of ~50% Ethanol (Smirnoff blue label vodka) to the flask to dissolve it and left it overnight, but it’s barely dissolved at all. I thought about heating it to create pure ethanol vapor which would do the trick but I don’t have a condenser to condense the ethanol again. Is there a better way of dissolving it?
This is all rust which has precipitated on the walls and it is very hard to remove it. You might have to use oxalic acid to remove rust stains on glass. Oxalic acid plays a dual role, it dissolves the rust like an acid, but it also complexes the iron, which prevents further hydrolysis and re-settling.