91, Protactinium (Pa)

gr. protos = vorher, vor dem Actinium

Säure-Base-Verhalten:

         
  Ce Pr Nd  
  Th Pa U  
   
         
   
 
   
   
   
   
   

Säure/Base-Verhalten der Protactinium-Oxide:

  Reaktionen mit:
HF
100%
H2SO4
conc.
HCl
20%
CH3COOH
25%
H2O NH3
25%
NaOH 10%
kalt
NaOH 50%
heiß
NaOH liq.
400°C
Pa2O5 PaOF3 (PaO)2(SO4)3 PaOCl3 PaO(CH3COO)3 PaO(OH)3 PaO(OH)3 PaO(OH)3 PaO(OH)3 PaO(OH)3
 
Legende: Lösung   Unlöslich   sauer →  neutral  → alkalisch  
 
 

pKS-Werte von Säure-Base-Paaren (HA + H2O ↔ H3O+ + A-) :

Säurename Formel pKS-Wert Basenname Formel pKB-Wert

Protactinium(IV)-Ion Pa4+ -0.80 Hydroxo-Protactinium(IV)-Ion Pa(OH)3+ 14.8
Hydroxo-Protactinium(IV)-Ion Pa(OH)3+ 0.14 Dihydroxo-Protactinium(IV)-Ion Pa(OH)22+ 13.86
Dihydroxo-Protactinium(IV)-Ion Pa(OH)22+ 0.38 Trihydroxo-Protactinium(IV)-Ion Pa(OH)3+ 13.62
Trihydroxo-Protactinium(IV)-Ion Pa(OH)3+ 1.25 Protactinium(IV)hydroxid Pa(OH)4 12.75

Protactinyl(V)-Ion PaO3+ 0.65 Hydroxo-Protactinyl(V)-Ion PaO(OH)2+ 13.35
Hydroxo-Protactinyl(V)-Ion PaO(OH)2+ 3.46 Dihydroxo-Protactinyl(V)-Ion PaO(OH)2+ 10.54
Dihydroxo-Protactinyl(V)-Ion PaO(OH)2+ 11.19 Protactinyl(V)hydroxid PaO(OH)3 2.81