DIY Phosphoric Acid solution

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beervoid

Hophead & Pellet Rubber
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Forgive me for asking if I have looked over it but I couldn't find any information on this here.

I would like to make my own phosphoric acid solution as it's much cheaper then the stuff we can buy from the homebrew shop here.

I found a seller that sells by the 1kg food grade phosphoric acid. I'm assuming it comes in crystal/powder form.
I've got a few questions.

How dangerous is it? (aside from wearing safety gloves and goggles since we are working with acid)
I'm assuming we would make a solution in either RO or distilled water?
What ratio's are we talking about if I would want to make a 10% phosphoric acid solution?
I guess it's not as easy as adding 10 grams in 1 liter.

Thank you!
 
What ratio's are we talking about if I would want to make a 10% phosphoric acid solution?
I guess it's not as easy as adding 10 grams in 1 liter.

Thank you!

10 grams in 1 litre would only be 1%, 100 grams in 1 litre is 10%, but that's w/v (mass per volume). You want w/w (mass per mass) which is 1 gram of acid for each 9 grams of water. I'd assume what you're looking at is actually 85% solution, in which case just use that as is rather than diluting. It's safer to use than other strong acids.
 
If you do want to dilute 85% phosphoric down to 10%, mix 11.76 grams of acid with water to make 100 grams.
 
10 grams in 1 litre would only be 1%, 100 grams in 1 litre is 10%, but that's w/v (mass per volume). You want w/w (mass per mass) which is 1 gram of acid for each 9 grams of water. I'd assume what you're looking at is actually 85% solution, in which case just use that as is rather than diluting. It's safer to use than other strong acids.

I can buy 1kg of phosphoric acid, I don't know what form it is in, im assuming it comes in powder crystals.
I preferably would like to make a 10% solution of this.

I'm not completely sure what you mean. 1 gram of acid in 9mililiters of water? is 10% solution?

so 100 grams in 900 mililiters for a 10% solution?
and 850 grams in 150 mililiters for a 85% solution?
 
I'm not completely sure what you mean. 1 gram of acid in 9mililiters of water? is 10% solution?

I've never seen Phosphoric acid crystals, although they do exist. I'd expect what you're looking at is an 85% solution.

Phosphoric acid percentages used in brewing are w/w (something I only learned recently on HBT). So a 10% solution is 1g of acid in 10g of solution, which is the same as 1g of acid mixed with 9g of water (close enough to 9mL of water; at 25C water has a density of 0.997g/mL).

If you have 85% solution, you need 1.18 grams of 85% acid made up with water to 10 grams of final solution to make a 10% solution (or 118g made up to 1000g).
 
I've never seen Phosphoric acid crystals, although they do exist. I'd expect what you're looking at is an 85% solution.

Phosphoric acid percentages used in brewing are w/w (something I only learned recently on HBT). So a 10% solution is 1g of acid in 10g of solution, which is the same as 1g of acid mixed with 9g of water (close enough to 9mL of water; at 25C water has a density of 0.997g/mL).

If you have 85% solution, you need 1.18 grams of 85% acid made up with water to 10 grams of final solution to make a 10% solution (or 118g made up to 1000g).
Ok I think I will have to double check with the supplier what kind of phosphoric acid im dealing with here.
Thank you for answering
 
Either way, it's not too hard to use and is much safer to work with than Hydrochloric or Sulphuric acids.
 
Anhydrous and crystalline state 100% phosphoric acid does exist, but it is very aggressively hygroscopic, and it absorbs water from the humidity of the air very rapidly as it rather quickly transitions into a liquid. I would not advise its use at such a concentration.
 
Anhydrous and crystalline state 100% phosphoric acid does exist, but it is very aggressively hygroscopic, and it absorbs water from the humidity of the air very rapidly as it rather quickly transitions into a liquid. I would not advise its use at such a concentration.
Noted, I'm waiting for a reply from my supplier.. I'm guessing it's the liquid form.
 
You will need to know the strength of what you are buying. The clue to this is the density of the solution. So measure that (use a hydrometer, weigh 1 cc) or find that on the label and we can tell you what dilution to use.
 

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