Inorganic Compounds in aqueous solution Flashcards
What colour is the copper hexaaqua ion
Blue
What colour is the Iron ll hexaaqua ion
Green
What colour is the Iron lll hexaaqua ion
Violet
What colour is the Aluminium hexaaqua ion
Colourless
What colour is the cobalt hexaaqua ion
Pink
Colour isn’t required
What is the general structure of Aqueous Metal Ions
Coordinate bond between metal and OH2
Metal Ion (electron pair acceptor)
Ligand (electron pair donor)
Covalent bond betwwen H and O in OH2
What pH are metal aqua ions
Acidic
Why are metal aqua ions acidic
The metal ion weakens OH bond and releases H+ ion
Depends on charge and size of ion
Known as hydrolysis
What is the general formula for hydrolysis of metal aqua ions
[M(H2O)6]n+ + H2O -> [M(H2O)5OH]n-1 + H3O+
What molecule causes the acidity in metal aqua ions
H3O+
Why are M3+ ions more acidic than M2+ ions
Equilibrium lies further to the right for M3+ than for M2+
What does acidity depend on
Charge on the Ion
Size of the ion
What are the most acidic types of metal ions
Small and highly charged metal ions are the most acidic
What happens to the equilibrium when alkali is added to the hydrolysis reaction
Equilibrium shifts right to replace the H3O+ ions lost by the reaction with OH-
What happens to the equilibrium when acid is added to the hydrolysis reaction
Equilibrium shifts to the left to undo the increase in H3O+ ion concentration
What are the 3 types of reactions that metal-aqua ions undergo
Hydrolysis (break an OH bond)
Substitution (break an M-O bond)
Redox (add or remove e-)
What do hydrolysis reactions form
Metal hydroxides
What are the 3 reagents to form metal hydroxides via hydrolysis
OH-
Dilute NH3
CO3 2-
What does the reaction of OH- with M2+ and M3+ form
[M(H2O)4(OH)2]
[M(H2O)3(OH)3] - some may react further (amphoteric hydroxides)
What does the reaction of dilute NH3 with M2+ and M3+ form
[M(H2O)4(OH)2]
[M(H2O)3(OH)3]
May get further reaction with excess NH3
What does the reaction of CO3 2- with M2+ and M3+ form
MCO3
[M(H2O)3(OH)3] + CO2 + H2O
What are the possible reagents for substitution reactions
XS or concentrated NH3
Cl- (concentrated HCl)
What does the reaction with XS NH3 form
Amine complexes
What does the reaction with Cl- form
Chloro complexes
What happens during a redox reaction
The oxidation state of the metal is changed
What is the formula and colour of aqueous copper ion
[Cu(H2O)6]2+ = blue solution
Equlibrium in water is:
[Cu(H2O)6]2+ + H2O <> [Cu(H2O)5OH]+
+ H30+
What is the reaction of Cu2+ with NaOH dropwise
[Cu(H2O)6]2+ + 2OH- <> [Cu(H2O)4(OH)2] + 2H20
Blue solution to Blue precipitate
What is the reaction of Cu2+ with NH3 dropwise
[Cu(H2O)6]2+ + 2NH3 <> [Cu(H2O)4(OH)2] + 2NH4+
Blue solution to Blue precipitate
What is the reaction of Cu2+ with excess NH3
[Cu(NH3)4(H2O)2]2+
Very Deep Blue solution
What is the reaction of Cu2+ with Na2CO3
CuCO3
Green Precipitate
What is the reaction of Cu2+ with concentrated HCl
[CuCl4]2-
Yellow/Green solution
What is the Formula and colour of aqueous Fe2+ ion
[Fe(H2O)6]2+ + H2O <> {Fe(H2O)5OH]+ + H3O+
Green Solution
What is the reaction of Fe2+ with NaOH dropwise
[Fe(H2O)6]2+ + 2OH- <> [Fe(H2O)4(OH)2] + 2H2O
Green solution to green/grey precipitate
Dirty Green
What is the reaction Fe2+ with NH3 dropwise
[Fe(H2O)6]2+ + 2NH3 <> [Fe(H2O)4(OH)2] + 2NH4+
Green Solution to green/grey Precipitate
What is the reaction of Fe2+ with Na2CO3
FeCO3
Green precipitate
Maybe slightly grey
What is the formula and colour of aqueous Fe3+ ion
[Fe(H2O)6]3+ + H2O <> [Fe(H2O)5OH]2+ + H3O+
[Fe(H2O)6]3+ = Pale Violet
{Fe(H2O)5OH]+ = Yellow/Brown
What is the reaction of Fe3+ with NaOH dropwise
[Fe(H2O)6]3+ + 3OH- <> [Fe(H2O)3(OH)3] + 3H2O
Red/Brown Precipitate
What is the reaction of Fe3+ with NH3 dropwise
[Fe(H2O)6]3+ + 3NH3 <> [Fe(H2O)3(OH)3] + 3NH4+
Red/Brown Precipitate
What is the reaction of Fe3+ with Na2CO3
2[Fe(H2O)6]3+ + 3CO3 2- <> 2[Fe(H2O)3(OH)3] + 3CO2 + 3H2O
Red/Brown Precipitate
What is the Formula and colour of aqueous Al3+ ion
[Al(H2O)6]3+ + H2O <> [Al(H2O)5OH]2+ + H3O+
Colourless Solution
What is the reaction of Al3+ with NaOH dropwise
[Al(H2O)6]3+ + 3OH- <> [Al(H2O)3(OH)3] + 3H2O
White precipitate
What is the reaction of Al3+ with excess NaOH
[Al(H2O)6]3+ + 4OH- <> [Al(H2O)2(OH)4]- + 4H2O
Colourless Solution
What is the reaction of Al3+ with NH3 dropwise
[Al(H2O)6]3+ + 3NH3 <> [Al(H2O)3(OH)3] + 3NH4+
White Precipitate
What is the reaction of Al3+ with excess NH3
[Al(H2O)3(OH)3]
White precipitate
What is the reaction of Al3+ with Na2CO3
2[Al(H2O)6]3+ + 3CO3 2- =2[Al(H2O)3(OH)3] + 3CO2 + 3H2O
White Precipitate
What is the reaction of Co2+ with concentrated HCl
[Co(H2O)6]2+ -> [CoCl4]2-
Pink to Blue
What is the reaction of Co2+ with excess NH3
[Co(H2O)6]2+ -> [Co(NH3)6]2+
Pink to yellowish brown solution
What is the reaction of Co2+ with NaOH
[Co(H2O)6]2+ -> [Co(H2O)4(OH)2]
Pink solution to blue/green precipitate that goes pink
What is the reaction of Co2+ with NH3 dropwise
[Co(H2O)6]2+ -> [Co(H2O)4(OH)2]
Pink solution to blue/green precipitate that goes pink
What is the reaction of [Co(H2O)4(OH)2] with excess NH3
[Co(NH3)6]2+
Yellowish brown solution
What is the reaction of [Co(NH3)6]2+ with air or H2O2
[Co(NH3)6]3+
Dark Blue
What is the reaction of [Co(H2O)4(OH)2] with air or H2O2
[Co(H2O)3(OH)3]
Pinkish/brown precipitate
What is the EDTA ion
EDTA 4-
What is the reaction of the Fe3+ ion with concentrated HCl
[FeCl4]-
[Fe(H2O)6]3+ + 4Cl- <-> [FeCl4]− + 6H2O
How do you convert Fe3+ into Fe2+
Zinc in acid