Is a negative pH value a definable pH value? Why or why not?

Question

Do you know the answer?

Answer 1

It's definable, it's just not possible in an aqueous solution. The ionization constant for water is 10^-14. Whatever the molar concentrations of OH-, or of H+, the product of the two must be 10^-14. So there is no way to actually make an aqueous solution such that the negative logarithm of the molar concentration of either the H+ or the OH- ions will be less than 0 or greater than 14.

Edit:
The answer below me is not correct. It's called the ionization CONSTANT for a reason. You can't protonate an entire sample of water. You will only shift the equilibrium. Remember Le Chatlier's principle.
If you keep adding acid, once the entire allowable concetration of H+ ions is reached, no more acid will ionize. Maybe you should open up your general chemistry book for a second look, you may have missed something.

Answer 2

The above answer is not correct.
If H+ ion concentrations are greater than 1M, then the pH actually goes below zero and continues to fall as the concentration goes up. This does not happen to an infinite extent, however, because as the acid gets more and more concentrated (above 5M) there is not enough water to ionise the acid, so pH rises again.