I’d like to start experimenting with using 10% phosphoric acid to acidify my mash and sparge water for my low-SRM beers. I’m using the Bru’nWater to calculate the amounts to use, but the amounts to use are expressed in milliliters (and partial teaspoons).
I don’t really have a good way to accurately measure volumes at that scale. But I do have a reasonably accurate (0.01 gram) scale. So if knew the density (g/ml) of my acid, I could just weight it out in grams.
Wikipedia tells me that phosphoric acid has a density of 1.885 g/ml, and that an 85% solution has a density of 1.685 g/ml. I guess I don’t understand the formula one uses to arrive at that 85% value, so I am not sure how to then get to the density of a 10% solution.
I know I could just assume 1g/ml, and it would be kinda close. I just like knowing stuff. My best guess is somewhere around 1.05 g/ml. Does anybody know the actual value (at room temp, sea level, etc).?
Pretty good guess. It is actually 1.053 g/l per the CRC handbook. Just a word of caution, brewing water spreadsheets only give a ballpark number for additions of acid IME.
Alternatively, you can buy a measuring thingy at the pharmacy for measuring liquid medicine to give to kids. These things are marked in 1-ml increments.
This actually made me laugh out loud. After over 6 months of ear infections with our daughter, we had a small drawer full of these. They do work great for measuring small amounts of liquids.
I doubt you’ll need a level of precission higher than what you would have access to with a standard measuring spoon set.
I use 10% phosphoric acid to acidy my sparge water, and I find that even when I’m using 100% RO water the amount of acid necessary is around 1/4 of a teaspoon (per 3.7 gallons of sparge water).
