Solve the problem.

Question

The pH of a solution ranges from 0 to 14. An
acid has a pH less than 7. Pure water is neutral
and has a pH of 7. The pH of a solution is
given by pH = - log x where x represents the
concentration of the hydrogen ions in the
solution in moles per liter. Find the hydrogen
ion concentration if the pH = 2.4.

Answer 1

The easiest way to do this is to just raise 10 to the negative value of the pH.  Thus, in this case hydrogen ion concentration would be 1x10^-2.4.   However, one doesn't usually leave it that way, so you put it in to the more conventional form as 

3.98x10^-3 and this would be the hydrogen ion concentration.  If you take the negative log of this number (pH) you will get 2.4.