Respuesta :

TSO
pH = -log([H+])
[H+] = 10^(-pH)

[H+] = 10^(-9)

[H+][OH-] = Kw
Kw = 1.0*10^-14 at 25 degrees celsius.

[OH-] = Kw/[H+] = (1.0*10^-14)/(1*10^-9) = 1.0*10^-5

The concentration of OH- ions is 1.0*10^-5 M.