Question

Which describes the relationship between [H+] and [OH−] ?

Answer 1

H+ is for an acid, which has a pH of 1-7. OH- is for a base, called hydroxide, and has a pH of 7-14.

pH 7 is neutral.

Answer 2

There are quite a few relationships between [H+] and [OH−] ions. And because there is a large range of number between 10 to 10-15 M, the pH is used. pH = -log[H+] and pOH = -log[OH−]. In aqueous solutions, [H+ ][OH- ] = 10-14. From here we can derive the values of each concentration.

-log[H+ ] + -log[OH- ] = -log[10-14]
pH + pOH = 14
So pH = 14 – pOH and pOH = 14 – pH

A neutral solution occurs when pH = pOH = 7. It is an acid solution when [H+ ] > [OH- ], pH < 7 and basic when [H+ ] < [OH- ], pH > 7.