15.2 Flashcards
what are the 4 main reactions transition metals undergo
redox
acid-base reaction
ligand exchange
coordination number change
what is an acid-base reaction
one or more ligand gains or loses a hydrogen ion
what is a ligand exchange
one or more ligand around the transition metal is replaced by a different ligand
what is a coordination number change
number of ligands change
what happens in the oxidation of Fe (iron)
oxidation number goes from 2+ to 3+
goes from a pale green to yellow/brown
what is observed when aqueous sodium hydroxide is added to copper(II) sulfate solution
pale blue solution forms a blue precipitate
what is the equation for the reaction between aqueous sodium hydroxide and copper(II) sulfate solution
[Cu(H2O)6]2+ + 2OH- -> [Cu(H2O)4(OH)2] + 2H2O
what type of reaction is the reaction between aqueous sodium hydroxide and copper(II) sulfate solution and why
acid-base reaction because the 2 hydroxide ions have removed hydrogen ions from the water ligands
what is amphoteric behavior
the ability of a species to react with both acids and bases
what happens when acid is added to tetraaquadihydroxocopper [Cu(H20)4(OH)2]
the blue precipitate disappears as the hydrogen ions react with the hydroxide ligands and convert them back to water ligands to form hexaaquacopper(II) which is a blue solution
what reaction occurs when a small amount of ammonia solution is added to hexaaquacopper(II)
ammonia acts as a base
[Cu(H2O)6]2+ + 2NH3 -> [Cu(H2O)4(OH)2] + 2NH4+
blue solution -> blue precipitate
what reaction occurs when excess ammonia solution is added to hexaaquacopper(II) (copper sulfate solution)
ligand exchange reaction
precipitate dissolves forms dark blue solution
[Cu(H2O)6]2+ + 4NH3 -> [Cu(NH3)4(H2O)2]2+ + 2H2O + 2OH-
what reaction occurs when concentrated hydrochloric acid is added to hexaaquacopper(II) (copper sulfate solution)
ligand exchange
coordination number change
[Cu(H2O)6]2+ + 4Cl- <=> [CuCl4]2- + 6H2O
blue -> green -> yellow
what is the name of the ion [CuCl4]2-
tetrachlorocuprate(II)
what reaction occurs between hexaaquacobalt(II) and alkalis
[Co(H2O)6]2+ + 2OH- -> [Co(H2O)4(OH)2] + 2H2O
pink solution -> blue precipitate
acid-base reaction
when left standing the solution goes back to pink
what reaction occurs when a small amount of ammonia is added to hexaaquacobalt(II)
[Co(H20)6]+2 + 2NH3 -> [Co(H2O)4(OH)2] + 2NH4+
acid-base reaction
pink solution -> blue precipitate
what reaction occurs when excess ammonia is added to hexaaquacobalt(II)
[Co(H2O)6]2+ + 6NH3 -> [Co(NH3)6]2+ + 4H2O + 2OH-
ligand exchange
pink solution -> blue precipitate -> brown solution
what happens to the brown solution [Co(NH3)6]2+ when left standing in air
it is oxidised from cobalt +2 to +3 and the solution goes yellow but is still a very dark solution due formation of other products
what reaction occurs between hydrochloric acid and hexaaquacobalt(II)
[Co(H2O)6]2+ + 4Cl- -> [CoCl4]2- + 6H2O
ligand exchange
change in coordination number
pink solution -> blue solution
what reaction occurs between hexaaquairon(II) and aqueous sodium hydroxide
[Fe(H2O)6]2+ + 2OH- -> [Fe(H2O)4(OH)2] + 2H2O
acid base reaction
pale green solution -> green precipitate
what reaction occurs between hexaaquairon(II) and ammonia
[Fe(H2O)6]2+ + 2NH3 -> [Fe(H2O)4(OH)2] + 2NH4+
acid base reaction
pale green solution -> green precipitate
what happens when the green precipitate [Fe(H2O)4(OH)2] is left standing in air
the colour changes from a green precipitate to a brown precipitate because it has been oxidised by air to form [Fe(H2O)3(OH)3]
what reaction occurs between hexaaquairon(III) and aqueous sodium hydroxide
[Fe(H2O)6]3+ + 3OH- -> [Fe(H2O)3(OH)3 + 3H2O
acid base reaction
yellow brown solution -> brown precipitate
what reaction occurs when ammonia is added to hexaaquairon(III)
[Fe(H2O)6]3+ + 3NH3 -> [Fe(H2O)3(OH)3] + 3H2O
acid base reaction
yellow/brown solution -> brown precipitate
