[TOBOKKE]

Greetings to everyone,

So I have been recently studying the beauty of chemistry and acid-base reactions and come across a very complex problem, I think.
What I have to do is to neutralize a solution of KOH (potassium hydroxide) with two acids: phosphoric acid H₃PO₄ (75.6%w/w) and sulfuric acid H₂SO₄.
I came across this wonderful website (http://www.chembuddy.com/?left=pH-calculation&right=pH-salt-solution) that deduces the formula to calculate the pH of the mixed acid-base solution but it works for one acid only. What do I have to do to make it work for more than one acid?

I need to minimize the cost of acid usage, by imposing some restritions, therefore I need to have some kind of analytical method to determine the concentrations of the acid to have a pH of 7.

This online calculator does the job for me (http://www.webqc.org/phsolver.php), but I would like to understand this and do it by myself.
Can someone help me with this?

Thank you very much!

Gonçalo Aguiar

[Borek]

I came across this wonderful website (http://www.chembuddy.com/?left=pH-calculation&right=pH-salt-solution) that deduces the formula to calculate the pH of the mixed acid-base solution but it works for one acid only. What do I have to do to make it work for more than one acid?

You can use the same approach to write a system of equations for a more than one acid, then add an equation for the price - after that it is just a math to find the minimum price. Most likely it will mean using only one of the acids, not the mixture, so you can as well start calculating how much of both acids you need and selecting the cheaper approach.

[TOBOKKE]

I came across this wonderful website (http://www.chembuddy.com/?left=pH-calculation&right=pH-salt-solution) that deduces the formula to calculate the pH of the mixed acid-base solution but it works for one acid only. What do I have to do to make it work for more than one acid?

You can use the same approach to write a system of equations for a more than one acid, then add an equation for the price - after that it is just a math to find the minimum price. Most likely it will mean using only one of the acids, not the mixture, so you can as well start calculating how much of both acids you need and selecting the cheaper approach.

Ok thank you very much for the help. I think I've figured it out how to do it.