Acid-Base assumption

[kenhung123]

When we have some equation like HA + H2O => A- + H3O+
We know that [A-]=[H3O+]
But what if the coefficients are different? E.g. HA + H2O => 2A- + H3O+ (I know its unbalanced but you get what I mean)
Do we just do [A-]=2[H3O+]?

[98.40_for_sure]

It can't be different, because the acid is simply "donating" a proton, thus only the H+ is moving from one and onto another

[fady_22]

When we have some equation like HA + H2O => A- + H3O+
We know that [A-]=[H3O+]
But what if the coefficients are different? E.g. HA + H2O => 2A- + H3O+ (I know its unbalanced but you get what I mean)
Do we just do [A-]=2[H3O+]?

Well, a different reaction (and K value) is usually given for each ionisation, so it will almost always have a one to one ratio. But if that were to happen, that would be a safe assumption.

[kenhung123]

Oh ok, so I was worrying about something impossible haha!

Thanks for the help!

[kenhung123]

If Ka for a particular solution do we assume the pH is low and that the reactants are greatly ionised in water

[fady_22]

If Ka for a particular solution do we assume the pH is low and that the reactants are greatly ionised in water

You mean if it's high? If the Ka is high, then most of the acid molecules ionise, resulting in a low pH.

[98.40_for_sure]

Yeah i don't understand waht you're trying to say... but Ka = extent of ionisation = [H3O+]

pH is inversely related to [H3O+]

[kenhung123]

Yea high sorry.