so say I was mixing some nitric acid with some perchloric acid , both are strong acids, how would I calculate the pH knowing the amount an concentration of each in the solution (that's all that's in there!)

ice matrix equation+quadratic formula

ice matrix equation
??
what is the ice matrix equation??

i would guess that since both are strong acids, they would both dissociate completely, and you can just add the concentrations of H+ contributed by both. unless of course they're both so dilute on the scale of 10^-7 M and you need to factor in water, etc.

(i'm not a chem expert though)

the most dilute would be 10^-5

I tried adding them up, figuring both would 100% dissasociate, but I am not getting the answer I am supposed to be getting, perhaps I am just plugging things in wrong.

Does anyone know of a sure method

Is it that much different from acid- base reactions

My guess is the following:

pH = -log[H] where [H] is mols H+ / liter solution

so [H] = 10^-pH

Do this for each acid so you get the mols H+ / liter solution

Then when you mix the solutions, the new [H] will be ([H1]*V1 + [H2]*V2) / (V1 + V2) where V1 is the volume of the amount of acid 1 you mixed and vice versa for V2. The reason for this is that [H1]*V1 is the num mols of H+ from the first solution, [H2]*V2 is the num mols of H+ from the second solution, and V1 + V2 is the total volume so the total mols of H+ per volume is ([H1]*V1 + [H2]*V2) / (V1 + V2).

Then take the log (base ten) of that and negate it to get the pH.

I think this works, but I'm not really sure.

This seems to be the way my own studies as well as the replies here are going..... everyone seems to be pointing to just summing up the 100% disassociated hydrogen ions.

I'm down

thanks guys

Litmus paper.