Inorganic Reactions Flashcards

1
Q

How many water molecules are able to bond to one transition metal?

A

Six!

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2
Q

What is a Lewis Base?

A

An electron acceptor.

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3
Q

Gie an example of a Lewis acid-base reaction.

A

NH3(aq) + BF3(aq)—-> NH3BF3(aq)

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4
Q

What do Lewis acids and bases react to form?

A

Coordinate bonds.

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5
Q

Why is it that solutions containing metal-aqua ions are slightly acidic?

A

Because aqua-metal ions react with the water to form H3O+ ions - the metal-aqua ions behave as a weak acid.

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6
Q

Why is it that solutions containing metal-aqua 3+ ions are more acidic than solutions containing metal-aqua 2+ ions?

A

3+ ions have a high charge density than 2+ ions - they polarize the oxygen in the water more strongly. This weakens the OH bond in water, making it easier for it to release a proton.

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7
Q

Give the dissociation reaction of [Al(H2O)6]3+ in water.

A

[Al(H2O)6]3+ + H2O —-> [Al(H2O)5(OH)]2+ + H3O+

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8
Q

Give the overal hydrolysis reaction of [M(H2O)6]3+ to its precipitate.

A

[M(H2O)6]3+(aq) + 3H2O(l) —-> M(H2O)3(OH)3(s) + 3H3O+(aq)

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9
Q

How can a metal hydroxide be dissolved?

A

By the addition of the acid - this will turn the hydroxide into the highest oxidation state of the metal-aqua ion.

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10
Q

Which metal hydroxides dissolve in bases? Why and how do they do this?

A

Al(H2O)3(OH)3 and Cr(H2O)3(OH)3 are amphoteric and are able to react with a base by donating a proton to form a negative ion and water.

i.e. Al(H2O)3(OH)3(s)+ OH-(aq) —-> [Al(H2O)2(OH)4]-(aq) + H2O(l)

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11
Q

Why is it that adding ammonia to a solution makes it basic?

A

The ammonia reacts with the water to form ammonium and hydroxide ions.

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12
Q

How is it possible to form a non-soluble precipitate from a metal-aqua 2+ ion? Give an example reaction with [M(H2O)6]2+

A

By reacting a carbonate (i.e. Na2CO3)

[M(H2O)6]2+(aq) + CO32-(aq) <—-> MCO3(s) + 6H2O(l)

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13
Q

How is it possible to form a precipitate from a metal-aqua 3+ ion? What occurs in the reaction process for this that prevents the precipitate dissociating in acid?

A

By reacting the 3+ ions with a carbonate - the carbonate ions react with the H3O+, removing them from the solution and keeping the pH neutral.

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14
Q

What is the reaction between Cu (II) metal-aqua ions and NH3?

A

NH3 + H2O <—-> OH- + NH4+

[Cu(H2O)6]2+ + 2OH- —-> Cu(H2O)4(OH) + 2H2O

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15
Q

What is the reaction between Cr (III) metal-aqua ions and excess hydroxide ions?

A

[Cr(H2O)6]3++ 6OH-—-> [Cr(OH)6]3- + 6H2O

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16
Q

What happens to cobalt, copper and chromium metal-aqua ions when they are reacted with excess NH3?

A

The NH3 replaces the water ligands; all of them, apart from copper, which only gains 4 and keeps 2 H2O ligands.

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17
Q

What is the reaction between Aluminium aqua-metal ions and excess OH-?

A

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

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18
Q

What is the reaction between Fe (III) and excess hydroxide ions?

A

The same as without excessive hydroxide ions - Fe (III) does not behave amphoterically.

[Fe(H2O)6]3+ + 3OH- —-> Fe(H2O)3(OH)3 + 3H2O

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19
Q

What is the reaction between cobalt (II) metal-aqua ions and Na2CO3?

A

[Co(H2O)6]2+ + CO32- —-> CoCO3 + 6H2O

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20
Q

What is the reaction between Cr (III) metal-aqua ions and Na2CO3?

A

[Cr(H2O)6]3+(aq) + 3H2O(l) —-> Cr(H2O)3(OH)3(s)

The carbonate removes the H3O+ ions formed.

CO32- + H+ —-> HCO3-

HCO3- + H+ —-> H2O + CO2

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21
Q

What is the reaction between copper (II) metal-aqua ions and excess NH3?

A

[Cu(H2O)6]2+(aq) + 4NH3(aq) —-> [Cu(NH3)4(H2O)2]2+(aq) + 4H2O(l)

22
Q

Why is it that ligand substitution reactions usually entail a positive entropy change?

A

Because a substance of a higher entropy is more stable.

23
Q

Why is it that ligand exchange reactions evolve very little heat?

A

Because the strength of the bonds formed and the strength of the bonds broken is very similar - the reaction absorbs as much energy as it expels.

24
Q

What is the reaction between [Ni(NH3)6]2+ and 1,2-ethanediamine?

A

[Ni(NH3)6]2+ + 3NH2CH2CH2NH2 —-> [Ni(NH2CH2CH2NH2)3]2+ + 6NH3

25
Q

Why is it that bidentate ligands usually substitute unidentate ligands?

A

When bidentate ligands substitute unidentate ligands, the entropy of the solution increases because the number of possible states the it has increased - there are more particles in the solution after than before. This process is known as chelation.

26
Q

Why is it that EDTA4- replaces uni and bidentate ligands?

A

Because the complex is formed is of a higher entropy because EDTA4- is hexadentate and will release lots of particles by substituting multiple ligands - this further means that the solution formed (and hence complex) is also more stable.

27
Q

Why is it that replacing multidentate ligands with unidentate ligands is difficult?

A

Because it would require an increase in the entropy of the system.

28
Q

What is the reaction and colour change that occurs between Iron (II) in aqueous solution and non-excess ammonia? Why is this reaction able to occur?

A

[Fe(H2O)6]2+(aq) + 2NH3(aq) —-> Fe(H2O)4(OH)2(s) + 2NH4+(aq)

Pale green solution —-> Green p.p.t —-> Brown p.p.t.

The brown p.p.t. is Fe (III) hydroxide oxidized from Fe (II) hydroxide

This reaction actually involves the formation of hydroxide ions from the reaction between ammonia and water:

H2O + NH3 —-> NH4+ + OH-

29
Q

What is the reaction between Iron (II) ions in aqueous solution with excess ammonia?

A

Same as for little -

[Fe(H2O)6]2+(aq) + 2NH3(aq) —-> Fe(H2O)4(OH)2(s) + 2NH4+(aq)

Fe(H2O)4(OH)2(s) —-> Fe(H2O)3(OH)3(s)

Green solution —-> Green p.p.t. —-> Brown p.p.t.

30
Q

What is the reaction between aqueous Iron (II) ions and excess hydroxide ions?

A

The same as for little

Pale green solution —-> Green p.p.t. —-> Brown p.p.t.

31
Q

What is the reaction between aqueous Iron (II) ions and sodium carbonate?

A

[Fe(H2O)6]2+(aq) + CO32-(aq) —-> FeCO3(aq) + 6H2O(l)

Pale green solution —-> Green p.p.t.

32
Q

How is it possible to dissolve metal hydroxide precipitates? Why is it possible to dissolve them in this way?

A

By adding acid - it is possible to dissolve them this way because they actually exist in equilibrium with their solution states; adding acid shifts this equilibrium towards the solution.

33
Q

What is the reaction between aqueous Cobalt (II) ions and sparing amounts of hydroxide? What is the colour change for this reaction?

A

[Co(H2O)6]2+(aq)+ 2OH-(aq) —-> Co(H2O)4(OH)2(s) + 2H2O(l)

Pink/colourless solution —-> Blue p.p.t.

34
Q

What is the reaction between between excess hydroxide ions and aqueous cobalt (II) ions?

A

The same as for little

Colour change of pink/colourless solution —-> blue p.p.t.

35
Q

What is the reaction between Co2+ ions in water and excess ammonia?

A

[Co(H2O)6]2+(aq) + 6NH3(aq)—-> [Co(NH3)6]2+(aq)+ 6H2O(l)

Pink/colourless solution —-> Straw coloured solution

Has an intermediary p.p.t. formed which is blue

The final solution also oxidizes to its 3+ state in oxygen, turning the solution dark brown

36
Q

What is the reaction between [Co(H2O)6]2+ and sodium carbonate?

A

[Co(H2O)6]2+(aq) + CO32-(aq) —-> CoCO3(s) + 6H2O(l)

Pink/colourless solution —-> Purple p.p.t.

37
Q

What is the reaction between [Co(H2O)6]2+ and conc. HCl?

A

[Co(H2O)6]2+(aq) + 4Cl-(aq) —-> [CoCl4]2-(aq)+ 6H2O(l)

Pink/colourless solution —-> Blue solution

38
Q

What is the reaction between Cu (II) ions in aqueous solution and hydroxide ions?

A

[Cu(H2O)6]2+(aq) + 2OH-(aq) —-> Cu(H2O)4(OH)2(s) + 2H2O(l)

Pale blue solution —-> Pale blue p.p.t.

39
Q

What is the reaction between Cu2+ ions in water and excess sodium hydroxide?

A

The same as for little.

Pale blue solution —-> Pale blue p.p.t.

40
Q

What is the reaction between concentrated ammoniacal solution and Cu2+ ions in water?

A

[Cu(H2O)6]2+(aq) + 3NH3(aq) —-> [Cu(H2O)2(NH3)4]2+(aq) + 4H2O(l)

Pale blue solution —-> Dark blue solution

41
Q

What is the reaction between Na2CO3 and Cu2+ ions in aqueous solution?

A

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

Pale blue solution —-> Blue-green p.p.t.

42
Q

What is the reaction between aqueous Copper (II) and concentrated HCl acid?

A

[Cu(H2O)6]2+(aq)+ 4Cl-(aq) —-> [CuCl4]2-(aq) + 6H2O(l)

Pale blue solution —-> Yellow solution

43
Q

What is the reaction between Fe (III) ions in aqueous solution and hydroxide ions?

A

[Fe(H2O)6]3+(aq) + 3OH-(aq)—-> Fe(H2O)3(OH)3(s) + 3H2O(l)

Yellow solution —-> Brown p.p.t.

44
Q

What is the reaction between excess ammonia and Iron (III) ions?

A

Same as for litte;

Yellow p.p.t.—-> Brown p.p.t.

45
Q

What is the reaction between Fe (III) ions in water and sodium carbonate ions? What is observed when this reaction occurs?

A

2[Fe(H2O)6]3+(aq) + 3CO3-(aq) —-> 2Fe(H2O)3(OH)3(s) + 3CO2(g) + 3H2O(l)

Bubbling

Yellow solution —-> Brown p.p.t.

46
Q

Why is it that sodium carbonate only reacts with metal 2+ ions to form their carbonates and not metal 3+ ions?

A

2+ ions are not sufficiently acidic (they do not weaken their water ligands’ OH bonds enough) to liberate CO2 from the CO32- in sodium carbonate. When the carbonate reacts with a 3+ ion, it actually reacts with two protons produced from the hexaaquametal ion’s dissociation - this forms carbon dioxide and the metal precipitate is formed as a result of the loss of the protons.

47
Q

What is the reaction between chromium (III) in aqueous solution with ammonia?

A

[Cr(H2O)6]3+(aq)+ 3NH3(aq) —-> Cr(H2O)3(OH)3(s) + 3NH4+(aq)

Ruby solution —-> Green p.p.t.

48
Q

What is the reaction between [Cr(H2O)6]3+ and excess hydroxide ions?

A

[Cr(H2O)6]3+(aq) + 6OH-(aq) —-> [Cr(OH)6]3-(aq) + 6H2O(l)

Ruby solution —-> Green solution

49
Q

What is the reaction between chromium (III) ions in aqueous solution and excess ammonia?

A

[Cr(H2O)6]3+(aq) + 6NH3(aq)—-> [Cr(NH3)6]3+(aq) + 6H2O(l)

Ruby solution —-> Purple solution

50
Q

What is the reaction between chromium (III) ions in solution and sodium carbonate?

A

2[Cr(H2O)6]3+(aq) + 3CO32-(aq) —-> 2Cr(H2O)3(OH)3(s) + 3CO2(g) + 2H2O(l)

Ruby solution —-> Green p.p.t.

Bubbling

51
Q

What is the reaction between aqueous aluminium ions and excess hydroxide ions?

A

[Al(H2O)6]3+(aq) + 4OH-(aq)—-> [Al(OH)4]-(aq) + 6H2O(l)

Both of these are colourless solutions

52
Q
A