Aqueous Ions Flashcards
Define Brønsted-Lowry acid
Proton donor
Define Brønsted-Lowry base
Proton acceptor
What is a Lewis acid?
An electron pair acceptor
What is a Lewis base?
An electron pair donor
Under the Lewis theory of acidity, Brønsted-Lowry acids are still considered acids. Why?
They all donate protons and protons readily accept a pair of electrons
What do transition metal ions act as?
Why?
Lewis acids
They accept lone pairs from ligands
Explain why all aqueous solutions of Fe3+ are more acidic than that of Fe2+
Fe3+ is smaller with a higher charge
Fe3+ ionises O-H in water more than Fe2+, releasing more H+ ions
All charged species are a)____ in water so form b)______
a) soluble
b) solutions
If the product of a reaction is neutral it will be …
Insoluble in water and come out of the Solution forming a PPT
Equation for adding OH- to a metal 2+ complex
What does the OH- act as and why?
[M(H20)6]2+ + 2OH- —> [M(H2O)4(OH)2] +2H2O
A base because it steals a H+ from H2O ligand
When NH3 is added in small amounts to a metal 2+ complex what does it act similarly to and why?
What is the side product?
OH- ion
Both are bases so will remove protons from water
NH4+
When OH- or NH3 is added to a metal 3+ aqueous complex, what is the complex formed?
Why is a PPT formed?
[M(H2O)3(OH)3]
It is uncharged
Why can carbonate ions remove protons from M3+ complex aqua ions in the same way as OH-?
M3+ complexes have a high acidity to their charge/size ratio so carry out acid base reactions with carbonate ions
Protons are lost from water forming a neutral substance
Can carbonate ions remove protons from the M2+?
No as it is a weaker acid and instead forms a carbonate (ie a substitution reaction)
Define amphoteric
can act as an acid or a base
What can water molecules be replaced by in copper
One at a time by NH3 molecules in an excess of ammonia
What is the beginning and final complexes for the further reaction of Cu with an XS of ammonia?
Reactant: [Cu(H2O)4(OH)2]
Product: [Cu(NH3)4(H2O)2]2+
Why is the Cu complex with XS ammonia slightly distorted?
Cis or trans?
The Cu-O bond it shorter to the best arrangement is to have NH3 ligands in Square planar arrangement
Trans
What is [Fe(H2O)6]2+?
A Green solution
Observation when NaOH added to Iron (II) aqueous ion
Green PPT
Goes brown on standing in air
Formula for complex formed when Fe(II) aqua ion is added to NaOH
Fe(H2O)4(OH)2
Observation when NH3 added to Iron (II) aqueous ion
green PPT goes brown on standing in air
Observation when Na2CO3 added to Iron (II) aqueous ion
Formula of complex
Green PPT
FeCO3
Observation of normal Cu (II) aqueous ion
Blue solution
Observation when NaOH added to Cu (II) aqueous ion
Blue PPT
Observation when excess NaOH added to Cu (II) aqueous ion
No further change
Observation when NH3 added to Cu (II) aqueous ion
Blue PPT
Observation when excess NH3 added to Cu (II) aqueous ion
Formula of Complex formed
Deep blue solution
[Cu(H2O)2(NH3)4]2+
Observation when Na2CO3 added to Cu (II) aqueous ion
Formula of complex formed
Blue-green PPT
CuCO3
Observation when NaOH added to Fe (III) aqueous ion
Brown PPT
May look orange brown
Colour of Iron 3+ aqua Complex
Brown solution
Some [Fe(H2O)5(OH)]2+ being present
Observation when excess NaOH added to Fe (III) aqueous ion
NVC
Observation when NH3 added to Fe (III) aqueous ion
Brown PPT
Observation when excess NH3 added to Fe (III) aqueous ion
NVC
Observation when Na2CO3 added to Fe (III) aqueous ion
Formula of complex
Brown PPT and CO2 evolved
[Fe(H2O)3(OH)3]
What is Al(III) aqua ion?
Colourless solution
Observation when NH3 added to Al (III) aqueous ion
White PPT
Observation when excess NH3 added to Al (III) aqueous ion
NVC
Observation when NaOH added to Al (III) aqueous ion
White PPT
Observation when excess NaOH added to Al (III) aqueous ion
Formula
Colourless solution
[Al(OH)4]-
Observation when Na2CO3 added to Al (III) aqueous ion
White ppt
CO2 evolves
