DIY Phosphoric Acid solution

[beervoid]

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!

 

[Ozarks Mountain Brewery]

this is what i use, I've had that for 2 years and it's not even half empty

https://www.dudadiesel.com/choose_item.php?id=FGphos

 

[beervoid]

this is what i use, I've had that for 2 years and it's not even half empty

https://www.dudadiesel.com/choose_item.php?id=FGphos

Thanks for the link but im in Asia so hard to order from here

 

[Gnomebrewer]

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.

 

[Gnomebrewer]

If you do want to dilute 85% phosphoric down to 10%, mix 11.76 grams of acid with water to make 100 grams.

 

[beervoid]

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?

 

[Gnomebrewer]

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).

 

[beervoid]

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

 

[Gnomebrewer]

Either way, it's not too hard to use and is much safer to work with than Hydrochloric or Sulphuric acids.

 

[beervoid]

Either way, it's not too hard to use and is much safer to work with than Hydrochloric or Sulphuric acids.

Thanks, I'll be careful either way but that sounds comforting.

 

[Silver_Is_Money]

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.

 

[beervoid]

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.

 

[ajdelange]

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.