inorganic - reactions of ions in aqueous solutions

Question 1

when in aqueous solution without any other ions what is the complex called

Answer 1

-metal aqua ion

Question 2

what are metal aqua ions and what is their shape

Answer 2

-central metal ion
-surronded by six water ligands
-in an octohedral shape

Question 3

what is a lewis acid

Answer 3

-species that can bond by accepting a lone pair of electrons

Question 4

what is a lewis base

Answer 4

-species which can bond by donating a lone pair of electrons

Question 5

how does metal aqua ions act in accordance with lewis acid/base laws

Answer 5

-metal = lewis acid
-water = lewis base

Question 6

how does acidity change in metal aqua ions

Answer 6

-the higher the charge on the metal in the metal ion the more acidic
-this is because the higher charge density on the oxygen pulls the water more strongly
-this weakens the O-H bond results in more dissociation and pulls electrons to the O away from the H
-another H2O picks up the electrons from the O to form H3O+ - which is effectively H+
-so acidity increases
-water is said to be polarised

Question 7

what happens if a metal aqua ions reacts with a base

Answer 7

-hydrolysis takes place - the base removes the H+ pushing the equilibrium right - eg OH-, NH3 , CO3^2-
-insoluble neutral complex will form a precipitate
-addition of excess base the insoluble complex may react further - or may dissolve

Question 8

what 3 reactions con metal aqua ions undergo

Answer 8

-hydrolysis - loss of H+ from the H2O ligands - O-H bond breaks
-substitution - replacement of H2O by other ligands - metal -ligand bond breaks
-redox - metal changes oxidation state - gain or loss of electrons

Question 9

how do hydrolysis equations of metal aqua ions work

Answer 9

-lower the charge for the products
-produce a (H2O)x(OH)x and produce H+
-take number away from H2O and put in an OH and a water

Question 10

what is the pH of a solution with a +ve charge

Answer 10

7

Question 11

what is the pH of a solution with a 2+ charge

Answer 11

6

Question 12

what is the pH of a solution with a 3+ charge

Answer 12

3

Question 13

what is the pH of a solution with a 4+ charge

Answer 13

0

Question 14

what is the reaction of the iron (II) ion with NaOH

Answer 14

-add OH = green solution - green precipitate
[Fe(H2O)6]2+ (aq) + 2OH– (aq) → Fe(H2O)4(OH)2 (s) + 2H2O (l)
-excess OH = no vis change

Question 15

what is the reaction of iron (II) with ammonia

Answer 15

The ammonia behaves in the same way as sodium hydroxide as it is a base and removes protons from the water ligands; the overall reaction with ammonia is:

[Fe(H2O)6] 2+ (aq) + 2NH3 (aq) → Fe(H2O)4(OH)2 (s) + 2NH4+ (aq)

green solution

Question 16

what is the reaction of iron (II) with carbonate ions

Answer 16

With carbonate ions, the iron(II)carbonate precipitates out:

[Fe(H2O)6] 2+ (aq) + CO32- (aq) → FeCO3 (s) + 6H2O (l)

green solution

Question 17

what is the reaction of copper ion and NaOH

Answer 17

-blue solution to pale blue precipate
[Cu(H2O)6]2 + (aq) + 2OH– (aq) → Cu(H2O)4(OH)2 (s) + 2H2O (l)
-excess NaOH = no vis change

Question 18

what is the reaction of copper solution and ammonia

Answer 18

The ammonia initially behaves in the same way as sodium hydroxide as it is a base and removes protons from the water ligands

[Cu(H2O)6] 2+ (aq) + 2NH3 (aq) → Cu(H2O)4(OH)2 (s) + 2NH4+ (aq)

However, ammonia is a good ligand and in excess ammonia, the ammonia partially substitutes for water dihydroxytetraaminecopper(II)

Cu(H2O)4(OH)2 (s) + 4NH3 (aq) → [Cu(NH3)4(H2O)2 ]2+ (aq) + + 4H2O

dark blue ppt

Question 19

what is the reaction with copper ions and carbonate ions

Answer 19

[Cu(H2O)6] 2+ (aq) + CO32- (aq) → CuCO3 (s) + 6H2O (l)

green/blue solution

Question 20

what is the reaction of alumminium and NaOH

Answer 20

-white ppt formed
[Al(H2O)6]3+ (aq) + 3OH– (aq) → Al(H2O)3(OH)3 (s) + 3H2O (l)
-add excess NaOH
-white ppt dissolves as it can react further
[Al(H2O)3(OH)3] + OH- = [Al(H2O)2(OH)4]- + H2O

Question 21

what is the reaction of alumminium and ammonia

Answer 21

The ammonia behaves in the same way as sodium hydroxide as it is a base and removes protons from the water ligands; the overall reaction with ammonia is:

[Al(H2O)6] 3+ (aq) + 3NH3 (aq) → Al(H2O)3(OH)3 (s) + 3NH4+ (aq)

white ppt

Question 22

what is the reaction bwt aluminum ions and carbonate ions

Answer 22

Removal of the hydronium ions by carbonate ions pushes the equilibrium to the right and precipitates out the hydrated aluminium hydroxide

The overall equation can therefore shown as:

2[Al(H2O)6]3+ + 3CO32− (aq) → 2Al(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)

white ppt

Question 23

what is the reaction of iron (III) and NaOH

Answer 23

-green solution to red/brown ppt
-[Fe(H2O)4(OH)2] 3+ (aq) + 3OH– (aq) → Fe(H2O)3(OH)3 (s) + H2O (l)
-add excess - no vis change

Question 24

what is the reaction of iron (III) and ammonia

Answer 24

The ammonia behaves in the same way as sodium hydroxide as it is a base and removes protons from the water ligands; the overall reaction with ammonia is:

[Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)

brown solution

Question 25

what is the reaction of iron (III) and carbonate ions

Answer 25

the acidity of iron(III) ions removes the carbonate ion and produces bubbles of carbon dioxide, while the iron(III) precipitates out as the hydroxide The overall equation can therefore shown as: 2[Fe(H2O)6]3+ (aq) + 3CO32− (aq) → 2Fe(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l) brown ppt

Question 26

what happens when u add excess H+ to each of the solutions

Answer 26

-dissolves the precipitate

Question 27

what is the colour of the [Cu(H2O)6]2+ ion

Answer 27

blue

Question 28

what is the colour of the [Co(H2O)6]2+

Answer 28

pink

Question 29

what is the colour of the [Fe(H2O)6]2+

Answer 29

green

Question 30

what is the colour of the [V(H2O)6]2+

Answer 30

green

Question 31

what is the colour of the [Cr(H2O)6]3+

Answer 31

violet

Question 32

what is the colour of the [Fe(H2O)6]3+

Answer 32

pale violet

Question 33

what is the colour of the [Al(H2O)6]3+

Answer 33

colourless

Question 34

What is Ligand substitution

Answer 34

When one ligand in a complex is replaced by another

Question 35

How does the coordination number of a metal ion ligand change

Answer 35

If the ligands are of different sizes If larger there will be a decrease in coordination number

Question 36

Does the coordination number change if the ligands are the same size

Answer 36

No stays the same Eg ammonia and water liando are of similar size

Question 37

What is the chelate effect

Answer 37

Substitution of ligands that can form more coordinate bonds than the previous ligand

Question 38

How does entropy and enthalpy and Gibbs’s free energy apply to the chelate effect

Answer 38

Increase in entropy - increase in the number of particles - more disorder Negligible change in the enthalpy Therefore gibbs free energy is more negative - so the reaction is more feasible when there is a larger number of ligands

Question 39

What is a chelate

Answer 39

-complex ions with polydentate ligands - useful in removing d-block metal ions from solution

Question 40

What are chelating agents

Answer 40

Ligands that form more than 1 coordinate bond -good at binding to the metal ion and harder to be substituted

Question 41

What is the most stable ligand and why

Answer 41

EDTA4- as it forms 6 coordinate bonds from one ligand - therefore is harder to remove

Question 42

What are the next stable ligands after EDTA4-

Answer 42

C2O4- H2O Cl-

Question 43

how does vandaium have variable oxidation states

Answer 43

-vanadate ions (V) can be reduced to oxidised vanadium species with the oxidation states I, III , IV by using zinc in acidic conditions

Question 43

what is the oxidation state of VO2^+

Answer 43

+5

Question 43

what is the oxidation state of VO^2+

Answer 43

+4

Question 43

what is the oxidation state of V^3+

Answer 43

+3 - ion so it has the same ox state as the charge

Question 43

what is the colour of VO2^+

Answer 43

yellow

Question 43

what is oxidation state of V^2+

Answer 43

+2 - so it has the same ox state as the charge

Question 43

what is the colour of VO^2+

Answer 43

green

Question 43

what is the colour of V^2+

Answer 43

violet

Question 43

how can V^2+ be confused with V^3+

Answer 43

V2+ is oxidised in air, therefore to observe the V2+, the test tube may need a stopper once the reduction has begun. Otherwise it turns back green because of its contact with oxygen in the air. It is oxidised back to vanadium(III).

Question 43

what is the colour of the V^3+

Answer 43

blue

Question 43

what is the reaction and colour of the [Cr(H2O)6]3+ ion and NaOH

Answer 43

green ppt [Cr(H2O)3(OH)3] excess NaOH green ppt [Cr(H2O)2(OH)4]-

Question 44

what is the reaction and colour of the [Cr(H2O)6]3+ ion and NH3

Answer 44

[Cr(H2O)3(OH)3] green ppt excess NH3 violet [Cr(NH3)6]2+

Question 45

what is the reaction and colour of the [Cr(H2O)6]3+ ion and CO32-

Answer 45

[Cr(H2O)3(OH)3] green ppt

Question 46

what is the reaction of [Cu(H2O)6]2+ and HCl

Answer 46

[CuCl4]2- yellow solution

Question 47

what is the reaction bwt [Co(H2O)6]2+ and NaOH

Answer 47

dilute [Co(H2O)4(OH)2] blue ppt excess is the same

Question 48

what is the reaction bwt [Co(H2O)6]2+ and NH3

Answer 48

dilute [Co(H2O)4(OH)2] blue ppt excess [Co(NH3)6]2+ yellow/straw solution

Question 49

what is the reaction bwt [Co(H2O)6]2+ and CO3^2-

Answer 49

CoCO3 pink ppt

Question 50

what is the reaction bwt [Co(H2O)6]2+ and HCl

Answer 50

[CoCl4]2- blue solution

Question 51

Give an equation to show how the complex ion Z can act as a Brønsted–Lowry acid with water

Answer 51

[Al(H2O)6]3+ + H2O = [Al(H2O)5(OH)]2+ + H3O+