colours of ions

• Cr3+?

  green or violet
• Cr2O7^2-?

  orange
• Mn2+?

  pale pink
• Fe2+?

  pale green
• Fe3+?

  yellow
• Co^2+

  pink
• Ni2+?

  green
• Cu2+?

  blue
• [Cu(H2O)6]2+

  blue ppt
• [Cu(NH3)4(H2O)2)]2+ ?

  deep blue solution
• [Co(H2O)6]2+ ?

  pink
• [CoCl4]2−?

  blue
• CoCO3?

  a purple solid
• [CuCl4]2-?

  yellow
• oxidising [Co(NH3)6]2+ to a 3+ requires H2O2 and undergoes a colour change of pale yellow to dark brown
• [Co(H2O)6]2+ ?

  pink
• [Co(H2O)6]3+?

  dark brown
• [Co(NH3)6]2+?

  straw
• CuCO3?

  a green ppt
• extraction of copper metal from a dilute aq solution using scrap iron?

  Cu2+ (aq) + Fe (s) —--> Cu (s) + Fe2+(aq)
• accepting electrons pairs from water makes something a lewis acid, donating protons makes it a Bronsted-Lowry acid
• why the PH of a solution containing Fe2+ ions is higher than that of a solution containing Fe3+ ions?

  because Fe2+ has a smaller charge to size ratio, and so is less polarising and doesn’t weaken the O-H bonds
• FeCO3?


  green ppt