Autoionización H2O
H2O <--> H+ + OH–
Kc = [H+] . [OH–] / [H2O]
Kc. [H2O] = [H+] . [OH–], Kc. [H2O] = Kw
Kw = [H+] . [OH–]
Kw solo depende de la temperatura.
A 25 ° C Kw = 10-14 prostituta
H2O puro: solución neutra
[H+] . [OH–] = 10-14
[H+] = 10-7
[OH–] = 10-7
Solución ácida
[H+] > [OH–]
[H+] > 10-7 prostituta
[OH–] <10-7 prostituta
Solución básica
[OH–] > [H+]
[OH–] > 10-7 prostituta
[H+] <10-7 prostituta
pH: potencial hidrogénico
Indica la acidez de una sustancia.
pH = -log [H+]
Solución neutra:
[H+] = 10-7
pH = -log 10-7
pH = 7
pOH: potencial hidroxiliónico
Indica la basicidad de una sustancia.
pOH = -log [OH–]
Solución neutra:
[OH–] = 10-7
pOH = -log 10-7
pOH = 7
Nota,
pH = 7 y pOH = 7, podemos concluir que pH + pOH = 14
Solución ácida
pH <7 y pOH> 7
Solución básica
pH> 7 y pOH <7