In the pH system of acids and bases, are there 10^-7 loose ions per liter (at pH of 7) or per mole of solvent? (Or per mole of total substance?) Most places tell me that the number on the pH scale tells you the number of dissociated ions, in moles, per liter of substance.    But, Wikipedia's article pH says this....:

... For a commonplace example based on the facts that the masses of a mole of water, a mole of hydrogen ions, and a mole of hydroxide ions are respectively 18 g, 1 g, and 17 g, a quantity of $10^7$ moles of pure (pH 7) water, or 180 tonnes ($18\times10^7$ g), contains close to 1 g of dissociated hydrogen ions (or rather 19 g of H3O+ hydronium ions) and 17 g of hydroxide ions.

But, if there are 10^-7 moles of hydrogen cations (protons) per LITER, and one mole of protons is approximately one gram (as Wiki's example says), then there is one mole (one gram) of protons per 10^7 liters of water, right?  One gram of hydrogen cations per 10,000,000 liters?
As opposed to what Wiki says, claiming one gram of loose hydrogen ions per 180 tonnes of water?
(One liter of water weighs about one kilogram, and there are a thousand kilograms in a tonne, correct?)
EDIT: Wiki's section on pH and all the incorrect numbers have been corrected.
In the pH system of acids and bases, are there 10^-7 loose ions per
liter (at pH of 7) or per mole of solvent? (Or per mole of total
substance?)

In a rigorous sense none of the options is correct, because pH being approximated by molarity is an approximation itself. The problem lies in the measurement itself and pH should be
$$pH= -log (a_{H^+})$$
The pH probe &quot;senses&quot; the activity of hydrogen ions not the molarity. This is why the pH of 5 M HCl is not equal to $$pH= -log (5)$$
There are no free or loose hydrogen ions in water, like a bare proton, rather this proton is attached to a network of water molecules.
Wiki is talking about an approximation. 1 ton is equal 1000,000 grams, so 10$^7$ mole/g x 18 g $\ce{H2O}$ is indeed 180 t. This part is correct so far. Note the author must be following metric ton. The whole world does not follow the US ton.
1 liter of water weighs ~ 1000 grams. Then 1000 g water contains 10$^{-7}$ moles of $\ce{H+}$, and 18x10$^{7}$ g water should have 1.8 x 10$^{-2}$ mol $\ce{H+}$ or 0.018 g $\ce{H+}$. I don't get 1 g.