Chemistry Forum

Hi, I'm using phosphoric acid to clean cement off clay pavers. The acid is 85% proof and I'm neutralizing it with sodium bicarbonate before I wash it off. But I'm finding the bicarb leaves a film of white efflorescence. I've checked that I'm using the correct amount, as the ph in the test mix is 7. ...

Hi, I'm using phosphoric acid to clean cement off clay pavers. The acid is 85% proof and I'm neutralizing it with sodium bicarbonate before I wash it off. I'm finding the acid to be too viscous and it's not soaking into the grooves and fissures as I'd like it too. I don't want to dilute it with wate...

Hi, In an earlier post (see link below) I've asked for help with neutralizing phosphoric acid using bicarb. Due to the large area of application (180 sqm) that adds up to a lot of bicarb, which gets costly. My questions are: 1. Is there an alternative with a similar or higher ph to bicarb that might...

Thanks Graham for the effort.

Yes, it's definitely phosphoric acid (ortho) 85% and it's classed as S5. Looks like I'm going to have to suit up for this stuff!

Cheers,

Hi, Can somebody please clarify whether the formula for phosphoric acid is H3PO4 or H3PO3? KriggY went to some trouble to assist me with calculating the amount of bicarb needed to neutralize phosphoric acid, but I've since found a discrepency with the formula I gave. Also, I'm not sure where the 84....

Thanks KriggY,

Now I have no more excuses for not doing this job... darn!!

If you're interested, here's the link for my information on neutralizing phosphoric acid.

http://www.kchemistry.com/molarity.htm

Cheers

Hi, per mm of acid? dont you mean ml? Oops, yes, I meant ml. The product is called Phosphoric Acid Cleaner made by Spirit, and "contains 22% phosphoric acid solution". I'm using it undiluted. As for how much acid, I can only estimate that the entire job will require 1 litre. So, 1 litre of...

Hi, I’m using phosphoric acid (H3PO3) to clean cement off some brick pavers and I’d like to neutralize it with either bicarbonate of soda (NaHCO3) or quicklime (CaO) before washing it into the soil. I read on the net that because phosphoric acid has 3 hydrogen molecules and bicarbonate of soda h...