Reactions of Aqueous Ions

Lewis acid=

Electron pair acceptor

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lewis base

electron pair donator

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In formation of complex ions what is the ligand

Lewis base because it is donating a pair of electrons in the dative covalent bond

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and what is the metal ion

Lewis acid

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How are metal-aqua ions formed

in aqueous solution

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What is [M(H2O)6]^2+ limited to m=

Fe (green) and Cu (blue)

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What is [M(H2O)6]^3+ Limited to M

Al (colourless) and Fe (violet)

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In solution what does Fe(|||) appear

yellow/brown due to hydrolysis reactions

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When is violet colour only really seen

in solid hydrated salts that contain these complexes

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Equilibria that happens in aqueous solutions of metal ions [M(H2O)6]^2+ +H2O=

[M(H2O)5(OH)]+ +H3O+

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[M(H2O)6]^3+ +H2O=

[M(H2O)5(OH)]2+ +H3O+

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What has equilibria lead to

generation of acidic solutions with M3+ Ions and very weakly acidic solutions with M2+ ions

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What are the 3+ ions noticeably more

acidic

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What is the acidity of [M(H2O)6]^3+ greater than that of

[M(H2O)6]^2+ in terms of greater polarising power (charge/size ratio) of the 3+ metal ion

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the greater the polarising power the more

strongly it attracts the water molecules - this weakens the O-H bond so it breaks more easily

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What do the bases OH- and ammonia when in limited amount form

the hydroxide precipitates

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What do they form in

deprotonation acid bases reactions

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What is M(OH)2(H2O)4 (s) include

Cu blue ppt, Fe(||) green ppt

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What is M(OH)3(H2O)3 (s) include

Fe(|||) brown ppt, Al white ppt

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[Cu(H2O)6]^2+ (aq) +2OH- (AQ)

Cu(H2O)4(OH)2 (s) +2H2O (L)

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[Fe(H2O)6]^2+ (aq) + 2NH3 (aq)=

Fe(H2O)4(OH)2 (s) +2NH4+ (aq)

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[Al(H2O)6]3+ (aq) +3OH-=

Al(H2O)3(OH)3 (s) +3H2O

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[Fe)H2O)6]3+ (aq)+ 3NH3(aq)=

Fe(h2O)3(OH)3 (s) +3NH4^+ (aq)

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How can this process happen

Step wise removing 1 proton at a time

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[Al(H2O)6]3+ (aq) + OH- (aq)

[Al(H2O)5(OH)]2+ (aq) + H2O (l

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[Al(H2O)5(OH)]2+ (aq) + OH- (aq)

[Al(H2O)4(OH)2]+ (aq) + H2O (l)

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Here what Is the NH3 and OH- ions acting as

Bronsted-Lowry bases accepting a proton

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With excess NaOH what does the aluminium hydroxide do?

the aluminium hydroxide dissolves.

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What does Al become

[Al(OH)4]- (aq) colourless solution.

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Al(H2O)3(OH)3(s) +OH-(aq)

[Al(OH)4]-(aq)+3H2O(l)

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Why is This hydroxide is classed as amphoteric

because it reacts and dissolves in both acids and bases.

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Al(H2O)3(OH)3(s) +3H+(aq)

[Al(H2O)6]3+(aq)

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With excess NH3 what occurs

a ligand substitution reaction occurs with Cu and its precipitate dissolves to form a deep blue solution.

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what is This substitution is incomplete with

Cu.

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What does Cu become

Cu becomes [Cu(NH3)4(H2O)2]2+ deep blue solution

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Cu(OH)2(H2O)4(s) + 4NH3 (aq)

[Cu(NH3)4(H2O)2]2+ (aq) + 2H2O (l) + 2OH- (aq)

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In this reactions NH3 is acting as a

Lewis base donating an electron pair

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What do the The 2+ ions react differently to

the 3+ ions with carbonate solutions.

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What do the 2+ ions with carbonate solutions result in

MCO3 ppt being formed

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What is Cu and Fe(||)

blue/green, green

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Cu2+ (aq)+CO32-(aq)

CuCO3(s)

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[Cu(H2O)6]2++CO32-

CuCO3+6H2O

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Fe2+ (aq)+CO32-(aq)

)FeCO3(s)

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[Fe(H2O)6]2+ + CO32-

FeCO3+6H2O

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What are these

ppt reactions

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what do the The 3+ ions with carbonate solution form

a M(OH)3 ppt and CO2 gas is evolved.

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Al forms

white ppt of Al(OH)3 (H2O)3 + CO2

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Fe(III) forms

brown ppt of Fe(OH)3 (H2O)3 + CO2

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2[Fe(H2O)6]3+(aq) + 3CO32-(aq)

2Fe(OH)3(H2O)3(s) +3CO2 + 3H2O(l)

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2[Al (H2O)6]3+(aq) + 3CO32-(aq)

2Al(OH)3(H2O)3(s) +3CO2 + 3H2O(l)

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What are these classed as

These are classed as acidity reactions.

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What is MCO3 is formed with

2+ ions

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but M2(CO3)3 is not formed with

3+ ions.

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How is the The difference is explained by

the greater polarising power of the 3+ ion due to its higher charge density.

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Reactions of Aqueous Ions

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