Question

Can the pH of anything be less than 0 and greater than 14?

Answer 1

Sure pH can be negative or higher than 14. Below the definition of pH, in which "aH+" denotes the activity of hydrogen ions or just the concentration (approximately) of hydrogen ions in water solution.

pH=-1g(aH+)
However, in general we do not use pH to measure the activity of hydrogen ions, if pH is beyond the ranger from 0 to 14.

I hope the given information helps you. ^_^