What is the pH value for phosphoric acid?

Answer 1

It depends on the concentration. pH is the negative log of the concentration of H+ atoms in a solution (measured it molarity, mol/L). Phosphoric acid (H3PO4) has 3 Hs in it, so for every molecule of acid dissolved, there are 3H+ ions.

But Phosphoric acid isn't a strong acid, so it doesn't completely dissolve in water. You can tell whether an acid is strong or not by looking at the number of Os and Hs. If it has 2 more Os than Hs, it is strong.

One must look up how thoroughly the acid dissolves in water. By looking it up on wolframalpha, I find that for every mole of H3PO4

In the solution, 1.06 moles of H+ are present. So if I take the -log1.06, I find the pH of 1M phosphoric acid, which is 1.1.

Answer 2

2.14, 6.86 and 12.4 - phosphoric acid is a polyprotic acid, meaning that it can dissociate more than one hydrogen ion.

Answer 3

6.7 although it still most likely has another one that I am not quite sure of maybe around 1-2

Answer 4

pKa2 of HSO4- is 1.92

Answer 5

2