Aqueous Ions Flashcards
Give the formula and colour of hexa aqua Fe2+ ions
[Fe(H2O)6] 2+
Pale green solution
Give the formula and colour of hexa aqua Cu2+ ions
[Cu(H2O)6] 2+
Blue
Give the formula and colour of a hexa aqua Fe3+ ion
[Fe(H2O)6] 3+
Yellow/brown
What is the formula and colour of a hexagon aqua Al3+ ion
[Al(H2O)6] 3+
Clear and colourless
What is a bronsten-l lowery acid?
A substance that donates h+ ions
What is hydrolysis?
The breaking of bonds using water
What happens when a hexa aqua metal ion reacts with water?
There is a hydrolysis reaction
The charge on the metal ion causes the water ligand to be polarised.
If the metal ion have large enough polarising power, the bonds in water ligands are weakened, and they donate a proton to the surrounding water molecules
How does pKa determine how acidic a hexa aqua metal ion is?
If pKa is lower, the ion is more acidic and dissociates more and releases more H3O+/H+
How does the charge/ size ratio of a hexa aqua metal ion affect its acidity?
If the ion is smaller and highly charged it will be more acidic. Because the metal ion can polarise the water ligands more. The O-H bonds are weakened more readily and the H+ is more easily donated
What happens when a base (sodium hydroxide) is added to a hexa aqua metal ion?
An insoluble precipitate of the metal hydroxide is created.
A reversible reaction is created until the metal hydroxide is no longer charged.
What is the product and appearance when sodium hydroxide is added to [Fe(H2O)6] 3+ ?
[Fe(H2O)3(OH)3
Brown ppt
What is the product and appearance when sodium hydroxide is added to [Al(H2O)6] 3+ ?
[Al(H2O)3(OH)3]
White ppt
What does amphoteric mean?
A species that can act as both an acid and a base
What is the formula and appearance of aluminium hydroxide?
[Al(H2O)3(OH)3]
White ppt
Give the equation for when aluminium hydroxide reacts with an acid, give the appearance of the product
[Al(H2O)3(OH)3] + 3H+ —> [Al(H2O)6] 3+
Clear and colourless solution
Give the equation for when aluminium hydroxide reacts with a base, give the appearance of the product
[Al(H2O)3(OH)3] + OH- —> [Al(H2O)2(OH)4]- + H2O
Clear and colourless solution
Give the equation for when [Fe(H2O)6]2+ reacts with NaOH , what is the appeared of the product?
[Fe(H2O)6]2+ +2OH- —> [Fe(H2O)4(OH)2] +2H2O
Green ppt
What is the general equation and observations for the reaction between NaOH and a metal hexa aqua ion?
[M(H2O)6] 2+ + 2OH- —> [M(H2O)4(OH)2] + 2H2O
A ppt is formed
What are the observations between an Fe (II) hexa aqua ion and NaOH?
Goes from a pale green solution to a green ppt
What happens when [Fe(H2O)4(OH)2] is left to stand in the air?
Iron hydroxide is oxidised and turns brown
What are the observations when copper hexa aqua ion reacts with NaOH?
Goes from a pale blue solution to a blue ppt
Why can ammonia react with metal hexa aqua ions?
Because it is a weak base and metal hexa aqua ions are weakly acidic
What is the equation and observations when Fe (III) aqua ion reacts with ammonia?
[Fe(H2O)6] 3+ + 3NH3 —> [Fe(H2O)3(OH)3] + 3NH4 +
Yellow/ brown solution to brown ppt
What is the equation and observations when Al aqua ion reacts with ammonia?
[Al(H2O)6] 3+ + 3NH3 —> [Al(H2O)3(OH)3] + 3NH4+
Clear and colourless solution to a white ppt
What is the equation and observations when Fe (II) aqua ion reacts with ammonia?
[Fe(H2O)6] 2+ + 2NH3 —> [Fe(H2O)4(OH)2] + 2NH4+
Green solution to and green ppt
What is the equation sna observations when Cu (II) reacts with ammonia?
[Cu(H2O)6] 2+ + 2NH3 —> [Cu(H2O)4(OH)2] + 2NH4+
Pale blue solution to a blue ppt
What happens when an excess of ammonia is added to a Cu (II) hydroxide ppt? What is the equation and observations for this?
A new complex is formed by a ligand substitution reaction
[Cu(H2O)4(OH)2] + 4NH3 —> [Cu(H2O)2(NH3)4] 2+ + 2H2O + OH-
Blue ppt to deep blue solution
What is the overall equation between the Cu (II) hexa aqua ion and excess ammonia?
[Cu(H2O)6] 2+ + 4NH3 —> [Cu(H2O)4(OH)2] + 4H2O
What is the general equation and observations for when metal (II) hexa aqua ions react with NaCO3?
[M(H2O)6] 2+ + CO3 2- —> MCO3 + 6H2O
Insoluble metal carbonates are formed
What is the general equation and observations for when metal (III) hexa aqua ions react with NaCO3?
2[M(H2O)6] 3+ + 3CO3 2- —> 2[M(H2O)3(OH)3] + 3CO2 + 3H2O
Metal hydroxides and carbon dioxide is produced, and water
Why does Metal (III) hexa aqua ions form hydroxides when reacted with NaCO3 instead of metal carbonates?
They are stronger acids due to their higher charge to size ratio
What are the observations when Cu (II), Fe(II), Fe(III) or Al hexa aqua ions react with NaCO3?
Cu(II)- blue/green ppt
Fe(II)- green ppt
Fe(III)- brown ppt
Al- white ptt
Give the equation for when EXCESS NaOH reacts with [Al(H2O)6]3+ (e.g aluminium hydroxide is formed, and the reacts with excess NaOH )
[Al(H2O)6]3+ + 4OH- —> [Al(H2O)2(OH)4]- + 4H2O
