Reactions of transition metal ions in aqueous solution Flashcards
Name the formula formed when added to (aq) with Fe/Cu
[M(H2O)6]2+
Name the formula formed when added to (aq) with Al/Fe
[M(H2O)6]3+
What colour is [Cu(H2O)6]2+?
blue
What colour is [Fe(H2O)6]2+?
pale green
What colour is [Fe(H2O)6]3+?
yellow
What colour is [Al(H2O)6]3+?
colourless
What happens when metal hexa aqua ions react with NaOH?
-a little/a few drops of NaOH, all form a metal hydrogen precipitate
-with excess, only [Al(OH)3(H2O)3] dissolves to make a colourless solution
What is the equation for NaOH and [M(H2O)6]2+?
[M(H2O)6]2+ (aq) + 2OH- (aq) –> M(OH)2(H2O)4 + 2H2O(l)
What is the equation for NaOH and [M(H2O)6]3+?
[M(H2O)6]3+ (aq) + 3OH- (aq) –> M(OH)3(H2O)3 + 3H2O(l)
What colour is Al(OH)3(H2O)3?
white precipitate - dissolves in excess NaOH to form a colourless solution
What is the equation for excess NaOH and AlCl3?
Al(OH)3(H2O)3 + -OH(aq) –> [Al(OH)4]- (aq) + 3H2O (l)
What happens when metal hexa aqua ions react with NH3?
-all form precipitates with a little/few drops of ammonia
-with excess, only Cu2+ forms a complex containing NH3
What is the equation for NH3 and [M(H2O)6]2+?
[M(H2O)6]2+ (aq) + 2NH3(aq) –> [M(OH)2(H2O)4] (s) + 2NH4+ (aq)
What is the equation for NH3 and [M(H2O)6]3+?
[M(H2O)6]3+ (aq) + 3NH3(aq) –> [M(OH)3(H2O)3] (s) + 3NH4+ (aq)
What is the equation for [Cu(OH)2(H2O)4] (s) and excess ammonia?
[Cu(OH)2(H2O)4] (s) + 4NH3 (aq) –> [Cu(NH3)4(H2O)2]2+ (aq) + 2OH- (aq) + 2H2O(l)
partial ligand substitution
How can you determine the charge on a metal ion?
-adding Na2CO3(aq)
-all the M2+ form metal(II) carbonate precipitate, NO FIZZING/NO CO2 - not acidic enough to convert it to CO2
-all the M3+ form metal(III) hydroxide precipitate, FIZZING/CO2 GAS
What is the equation for M2+ and Na2CO3?
[M(H2O)6]2+ (aq) + CO3 2- –> MCO3(s) + 6H2O(l)
What colour is [Cu(NH3)4(H2O)2]2+ (aq)?
deep blue
What is the equation for M3+ and Na2CO3?
[M(H2O)6]3+ (aq) + 3CO3 2- –> 2M(OH)3(H2O)3 + 3CO2(g) + 3H2O(l)
[Cu(H2O)6]2+ (aq) + 4Cl- –>
blue
[CuCl4]2- + 6H2O (l)
yellow-green solution
[Fe(H2O)6]2+ (aq) + 4Cl- –>
pale green
[FeCl4]2- + 6H2O (l)
green solution
[Fe(H2O)6]3+ (aq) + 4Cl- –>
yellow
[FeCl4]- + 6H2O (l)
yellow
[Al(H2O)6]3+ (aq) + 4Cl- –>
colourless
[AlCl4]- + 6H2O (l)
colourless
What is special about Al(OH)3(H2O)3 ?
amphoteric - dissolves in both acids and alkalis
Why is M3+ more acidic than M2+?
-the M3+ ion is both smaller and more highly charged than the M2+ ion (it has a higher charge/size ratio)
-so is more strongly polarising
-the M3+ ion attracts electrons more strongly from the oxygen atoms of the water ligands, so weakens the O-H bonds in the water molecules more
-which releases more H+ ions, increasing [H+], making the solution more acidic
Use equations to show why is M3+ more acidic than M2+
[M(H2O)6]2+ (aq) + H2O(l) ⇌ [M(OH)(H2O)5]+ (aq) + H3O+ (aq)
[M(H2O)6]3+ (aq) + H2O(l) ⇌ [M(OH)2(H2O)5]2+ (aq) + H3O+ (aq)
How is VO2+ produced?
VO3- + 2H+ ⇌ VO2+ + H2O
orange ———yellow
acid-base, not redox
What is the colour of [V(H2O)6]2+?
purple
What is the colour of [V(H2O)6]3+?
green
What is the colour of [VO(H2O)5]2+?
blue
What is the colour of [VO2(H2O)4]+?
yellow
