Various Acids mEq/mL (or mEq/gram) acid strengths at Targeted pH

[Silver_Is_Money]

In trying to upgrade my understanding of pKa's and Ka's, I've written a few new spreadsheets, for which the combined answers derived (with respect to an acids nominal acid strength variation with respect to target pH) are as per the attached PDF file. The attached PDF is mainly oriented toward guidance in neutralizing sparge water to a target pH, but the valuations found therein should find many additional applications in mash or wort pH adjustment as well. Would someone please review these derived values and tell me if they are nominally correct across the board? If they are, I will know that my new pet project spreadsheets logic is on the right track.

 

[Silver_Is_Money]

Example for 32.5 Liters of 161 ppm alkalinity water, with a target of 5.7 pH, and with 75% Phosphoric acid chosen.
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161 ppm - 18 ppm = 143 ppm (mg/mL) of alkalinity required to be removed

MW of CaCO3 = 100.0869 g/mol = 100.0869 mg/mmol
CaCO3 valence = 2
Eq Wt of CaCO3 = MW/valence = 100.0869/2 = 50.04345 g/Eq = 50.04345 mg/mEq

143 mg/L / 50.04345 mg/mEq = 2.8575 mEq/L of alkalinity (as CaCO3)

2.8575 mEq/L x 32.5 L = 92.869 mEq's of alkalinity to be removed

92.869 mEq / 12.44 mEq/mL (acid strength at pH 5.70) = 7.47 mL of 75% phosphoric Acid to be added

Result should be 32.5 Liters of pH 5.7 water. Wherein admittedly this method does not account for the waters initial pH, so some generally slight final pH variation may occur.

 

[Silver_Is_Money]

The key is that for "weak acids" (such as for most acids used by home brewers) there is not a fixed acid strength that one can reference. The lower you desire to push the pH, the weaker a weak acid effectively becomes. That is the main thing of value in the PDF I included within the first post to this thread.

Among acids potentially used by brewers, only hydrochloric and sulfuric fall into the "strong acid" camp. Weak and strong are terms associated with H+ dissociation, or release. Strong acids release effectively all of their available H+ ions in water, whereas "weak acids" do not. And on top of this, what they do release is pH environment dependent.

 

[Gnomebrewer]

They look about the same as the numbers I use, which came from one of AJs posts a while ago.

Edit: From here
https://www.homebrewtalk.com/forum/threads/determining-acid-equivalents.627435/

 

[Silver_Is_Money]

They look about the same as the numbers I use, which came from one of AJs posts a while ago.

Edit: From here
https://www.homebrewtalk.com/forum/threads/determining-acid-equivalents.627435/

Thanks! PM me if you would like a copy of the spreadsheet that generated my mEq/mL (and/or mEq/gram) numbers. The formulas are not hidden within, and the lines are editable so any acid (or acid concentration percentage) of your choosing can be inserted.