Aqueous Chem

Question 1

What is anhydrous?
What is hydrated?
Write equation for hydrated to anhydrous copper
What do anhydrous solids dissolved form?
Write equation for reaction between CoCl2 and 6H2O
For +3 ions is the reaction exo or endo
Write equation for AlCl3 with xs H2O

Answer 1

Without water 
With water
CuSO4.5H2O = CuSO4+5H2O
Hexa Aqua ions
CuCl2+6H2O=[Cu(H2O)6]2+ +2Cl-
Very Exothermic 
AlCl3--xsH2O-->[Al(H2O)6]3+ +3Cl-

Question 2

Redox
What is it the change of?
Therefore it is the?
Write an equation for this with a 2+ ion

Answer 2

The charge on the central metal ion
Loss or gain of an electron
[M(H2O)6]2+>[M(H2O)6]3+ + e-

Question 3

Hydrolysis/acidity
What is set up when the ion is placed in water?
Write an equation for this of the [M(H2O)6]2+?
What is the ph of the solution and what is it therefore?
The same for [M(H2O)6]3+?
Why is it hydrolysis?
Why is it acidity?

Answer 3

Equilibrium
[M(H2O)6]2+ +H2O > [M(H2O)5(OH)]+ +H3O+
6 very weak acid
[M(H2O)6]3+ + H2O > [M(H2O)5(OH)]2+ + H3O+
[M(H2O)5(OH)]2+ +H2O >[M(H2O)4(OH)2]+ +H3O+
[M(H2O)4(OH)2]+ +H2O >[M(H2O)3(OH)3]+ +H3O
Ph 3
Because splits H2O to OH and H
Because it forms H3O+

Question 4

Why is [M(H2O)6]3+ more acidic than [M(H2O)6]2+?

What is the main species present in the solution?

Answer 4

Bigger mass to charge ratio
Weaker OH bond
Easier hydrolysis

Aqueous ions

Question 5

Define a Lewis acid.
What acts as a base?
Equation for reaction of H2O and H+
In a complex ion what is are the Ligands and what are the central metal ions with respect to Lewis acids and bases.
Draw the structural reaction of Cu2+ and 6H2O

Answer 5

An electron pair acceptor 
Molecule or ion with a lone pair of electrons 
H2O+H+>H3O+
Ligands=bases 
Central metal ions=acids

Question 6

Are metal hydroxides soluble in water?

What are metal hexaaqua ions reacted with to form metal hydroxides?

Answer 6

No

NaOH or NH3

Question 7

Reactions of Aqua ions and alkalis
Equations of M2+ and M3+ Aqua ions with NaOH
Equations of those that react with excess NaOH
Equations for M2+ and M3+ Aqua ions with NH3
Equations for those that react with excess
Equations for the M2+ and M3+ Aqua ions with NaCO3

Answer 7

[M(H2O)6]2+ +2OH- >[M(H2O)4(OH)2]+2H2O
[M(H2O)6]3+ +3OH- >[M(H2O)3(OH)3]+3H2O
[Cr(H2O)3(OH)3]+3OH- >[M(OH)6]3- +3H2O
[Al(H2O)3(OH)3]+3OH- >[Al(OH)4]- +3H2O

[M(H2O)6]2+ + 2NH3 >[M(H2O)4(OH)2]+2NH4+
[M(H2O)6]3+ +3NH3 >[M(H2O)3(OH)3]+3NH4+

[Cu(H2O)4(OH)2]+4NH3 >[Cu(NH3)4]2+ +2H2O+2OH-
[Co(H2O)4(OH)2]+6NH3>[Co(NH3)6]2+ + 6H2O
[Cr(H2O)3(OH)3]+6NH3>[Cr(NH3)6]3+ +6H2O

[M(H2O)6]2+ +CO32- > MCO3 +6H2O
2[M(H2O)6]3+ +3CO32- >[M(H2O)3(OH)3]+3CO2+3H2O

Question 8

Reactions of Aqua ions with alkalis (NaOH)
Why does equilibrium move to the right when OH- is added?
What’s the equation for the reaction of OH- and H3O+
What is added when the first equilibrium is completely displaced to the right?
What is this added in the form of?
Equation for the next step

Answer 8

To replace H3O+ reacting 
OH+H3O+ > 2H2O
More OH
H3O+
[M(H2O)5(OH)]+ + H3O+ > [M(H2O)4(OH)2]+H3O+

Question 9

Reactions of Aqua ion with alkalis 
 How can they be reversed?
Why do Cr and Al react with xs?
Equations 
What is observed?

Answer 9

Adding HNO3
Have greater mass to charge ratio and so are still weakly acidic after the first reaction so are able to react with more 
Ppt redissolves 
[Al(H2O)3(OH)3]+3OH->[Al(OH)4]+3H2O
[Cr(H2O)3(OH)3]+3OH->[Cr(OH)6]+3H2O

Question 10

Which metal hydroxides are amphoteric?
General equations of these hydroxides with HCl
What is observed?

Answer 10

Al and Cr
[M(H2O)3(OH)3]+3HCl > [M(H2O)6]3+ +3Cl-
Ppt redissolves

Question 11

Why is nitric acid preferred to others?

Answer 11

Because NO3- is a poor ligand

Question 11

Is NH3 a weak or strong base?
Equation for NH3 dissolving in water
Which metals react with xs NH3?

Answer 11

Weak
NH3+H2O> NH4+ + OH-
Cu,Co,Cr

Question 12

Reaction of 
Cu
Co
Cr
with xs NH3 

What happens with if you add H2O2 or leave [Co(H2O)4(OH)2] to stand in air?
Equation

Answer 12

[Cu(H2O)4(OH)2]+4NH3>[Cu(NH3)4(H2O)2]2+
+2H2O+2OH-
[Co(H2O)4(OH)2]+6NH3>[Co(NH3)6]2+ + 2H2O
+ 2OH-
[Cr(H2O)3(OH)3]+6NH3>[Cr(NH3)6]3+ +3H2O
+3OH

Is oxidised so colour darkens
[Co(NH3)6]2+ >[Co(NH3)6]3+ +e-

Question 13

Na2CO3
What does CO32- react with acid to form?
What does further addition of acid form?
What does carbonic acid rapidly decompose to?
Equations
Why do metal(II) not displace HCO3- from carbonates?
Why can metal(III)ions displace HCO3-?
What is observed?why?

Answer 13

Hydrogen carbonate 
Carbonic acid 
Co2 and h2o
CO32-+H3O+>HCO3-+H2O
HCO3-+H3O+>CO2+2H2O
Not strong enough
More acidic 
Effervescence be CO2 and H2O produced

Question 14

Substitution
What can the species be that substitute the water?
Equation for substitution with NH3 and M2+
Why is there no change in coordination number?
How is this reversed?
One water replaced at a time

Answer 14

Neutral or charged
[M(H2O)6]2+ +6NH3 > [M(NH3)6]2+ +6H2O
Bc NH3 isn’t charged and is similar size to H2O
Addition in HNO3

Question 15

Substitution 
   What is a good source for Cl-?
   Why is this better than NaCl?
   Equations with M2+
  How is this reversed?
    Why does repulsion occur?
   Why is HNO3 usually used?

Answer 15

HCl 
More soluble in water 
[M(H2O)6]2+ +4Cl- >[MCl]2- + 6H2O
Addition of water 
By the ligands are anions 
Bc NO3- is a poor ligand

Question 16

Substitution 
 What does substitution by a multidentate or bidentate ligand lead to? 
  What's this known as? 
  What does it lead to?
  Equation

Answer 16

More stable complex
Chelate effect
Increase in entropy be there’s more species on the product side
[M(H2O)6]2+ + EDTA>[M(EDTA)2- + 6H2O

Question 17

What bond does hydrolysis break?
What bond does substitution break?
What does redox change?5
Why does M3+ have a greater polarising power than M2+?
When is further hydrolysis especially likely and why?
Are metal hydroxides soluble?

Answer 17

OH
MO
charge on the central metal ion 
Greater mass:charge ratio
When base is added be it reacts with the H3O+ and upsets equilibrium 
No