Reactions of Ions A2 Flashcards
Why is an Fe3+ complex more acidic than an Fe2+ complex
Fe3+ is smaller and has a higher charge, so a larger charge density. This attracts electrons from the oxygen in water ligands and weakens the OH bond, allowing for H+ to be released
What occurs when a base is added to an complex
2/3 of the H2O is turned into OH- (base takes H+ from H2O), leaving a complex with no charge forming a precipitate
Why is there an Fe(II) carbonate but no Fe(III) carbonate
The carbonate can remove protons from an Fe3+ complex but cannot do the same with an Fe2+ complex (Fe3+ more acidic)
What does amphoteric mean
Shows both acidic and basic properties
What is an example of an amphoteric hydroxide
Al(H2O)3(OH)3
What is chelation
When the number of ligands bonded to a complex decreases due to a ligand substituting for a bidentate or a multidentate
Why is chelation energetically favourable
Increase in entropy as more product moles than reactants
What is an example of a multidentate
EDTA4-
What is the colour of [Fe(H2O)6]2+
Pale green
What is the colour of [Cu(H2O)6]2+
Pale blue
What is the colour of [Fe(H2O)6]3+
Pale yellow
What is the colour of [Al(H2O)6]3+
Colourless
What occurs when OH- is added to [Fe(H2O)6]2+
Deprotonated twice to form [Fe(H2O)4(OH)2]. No difference after excess added
What is the colour of [Fe(H2O)4(OH)2]
Green gelatinous precipitate
What occurs when NH3 is added to [Fe(H2O)6]2+
Deprotonated twice to form [Fe(H2O)4(OH)2]. No difference after excess added
What occurs when (CO3)2- is added to [Fe(H2O)6]2+
Green precipitate of FeCO3 is formed
What occurs when OH- is added to [Cu(H2O)6]2+
Deprotonated twice to form [Cu(H2O)4(OH)2]. No difference after excess added
What is the colour of [Cu(H2O)4(OH)2]
Pale blue precipitate
What occurs when NH3 is added to [Cu(H2O)6]2+
Little NH3 deprotonated twice. Excess NH3 does partial ligand substitution to form [Cu(NH3)4(H2O)2]2+
What is the colour of [Cu(NH3)4(H2O)2]2+
Deep blue solution
What occurs when (CO3)2- is added to [Cu(H2O)6]2+
Blue-green precipitate of CuCO3 is formed
What happens to [Fe(H2O)4(OH)2] after some time
Soon oxidises by air to brown [Fe(H2O)3(OH)3]
What occurs when OH- is added to [Fe(H2O)6]3+
Deprotonated thrice to form [Fe(H2O)3(OH)3]. No change in excess
What is the colour of [Fe(H2O)3(OH)3]
Brown gelatinous precipitate
What occurs when NH3 is added to [Fe(H2O)6]3+
Deprotonated thrice to form [Fe(H2O)3(OH)3]. No change in excess
What occurs when (CO3)2- is added to [Fe(H2O)6]3+
Deprotonated thrice to form [Fe(H2O)3(OH)3] and bubbles of CO2
What occurs when OH- is added to [Al(H2O)6]3+
Little OH- deprotonated to form [Al(H2O)3(OH)3]. Excess OH- forms [Al(OH)4]-]
What is the colour of [Al(H2O)3(OH)3]
White precipitate
What is the colour of [Al(OH)4]-]
Colourless solution as it’s charged
What occurs when NH3 is added to [Al(H2O)6]3+
Deprotonated thrice to form [Al(H2O)3(OH)3]. No change in excess
What occurs when (CO3)2- is added to [Al(H2O)6]3+
Deprotonated thrice to form [Al(H2O)3(OH)3] and bubbles of CO2
