tests for cations

• Al 3+ + NaOH =


  white ppt, soluble in excess, colorless solution
• NH4 + NaOH =


  ammonia produced on warming
• Ca2+ + NaOH =

  white ppt, insoluble in excess
• Cr3+ + NaOH =

  green ppt, soluble in excess
• Cu2+ + NaOH=

  light blue ppt, insoluble in excess
• Fe3+ + NaOH =

  red-brown ppt, insoluble in excess
• Zn2+ + NaOH=

  white ppt, soluble in excess, colorless solution
• Fe2+ + NaOH =

  green ppt, insoluble in excess, ppt turns brown
• Al3+ + NH4 =

  white ppt, insoluble in excess
• Ca2+ + NH4 =

  no ppt / slightly white
• Cr3+ + NH4 =

  green ppt, insoluble in excess
• Cu2+ + NH4 =

  light blue ppt, soluble in excess, dark blue solution
• Fe2+ + NH4 = 


  green ppt, insoluble in excess, ppt turns brown
• Zn2+ + NH4 =

  white ppt, soluble in excess, colorless solution