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A2 Chemistry - Unit 5 > Unit 3.5.5 - Reactions in Inorganic Compounds in Aqueous Solution > Flashcards

Unit 3.5.5 - Reactions in Inorganic Compounds in Aqueous Solution Flashcards

1
Q

What colour is [Cr(OH)₆]³⁻

A

Green solution

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2
Q

What is chelation?

A

When unidentate ligands are exchanged for bidentate or multidentate ligands.

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3
Q

Using the ∆G = ∆H - T∆S why is chelation always feasible?

A

∆H is very small and ∆S is very large and positive meaning ∆G is large and negative.

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4
Q

What is a Lewis acid?

A

Electron pair acceptor

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5
Q

What is the equation for the reaction between copper aqua ions and excess ammonia?

A

[Cu(H₂O)₆]²⁺(aq) + 4NH₃(aq) → [Cu(NH₃)₄(H₂O)₂]²⁺(aq) + 4H₂O(l)

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6
Q

What colour is Cu(H₂O)₄(OH)₂

A

Blue precipitate

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7
Q

What is the equation when ammonia is added to a metal aqua 3+ complex?

A

[M(H₂O)₆]³⁺(aq) + 3NH₃(aq) ⇋ [M(H₂O)₃(OH)₃(s) + 3NH₄⁺(aq)

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8
Q

What colour is [Cr(NH₃)₆]³⁺

A

Purple solution

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9
Q

What is a Lewis base?

A

Electron pair donor

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10
Q

In general how many water molecules form co-ordinate bonds with each metal ion?

A

6

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11
Q

Name two transition metals that are amphoteric?

A

Al³⁺ and Cr³⁺

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12
Q

What colour is [Co(NH₃)₆]²⁺

A

Straw coloured solution

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13
Q

Why don’t metal 3+ ions react with carbonates the same as metal 2+ ions?

A

Metal 3+ ions form more acidic solutions so are stronger acids.

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14
Q

When H₂O ligands are swapped for NH₃ ligands why doesn’t the co-ordination number or shape change?

A

Because the ligands are similar size and uncharged.

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15
Q

During ligand exchange, if the ligands are different sizes does the co-ordination and shape change?

A

Yes

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16
Q

What is the equation for the reaction between cobalt aqua ions and excess ammonia?

A

[Co(H₂O)₆]²⁺(aq) + 6NH₃(aq) → [Co(NH₃)₆]²⁺(aq) + 6H₂O(l)

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17
Q

What is the equation for the reaction between chromium aqua complex and EDTA⁴⁻?

A

[Cr(H₂O)₆]²⁺ + EDTA⁴⁻ → [Cr(EDTA)]²⁻ + 6H₂O

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18
Q

What colour is [CuCl₄]²⁻?

A

Yellow green solution

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19
Q

When is ligand exchanged not easily reversed?

A

When the new complex ion is more stable than the old one.

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20
Q

What colour is [Cr(H₂O)₆]³⁺

A

Violet solution

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21
Q

Co-ordinate bonds are formed between which sort of bases and acids?

A

Lewis

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22
Q

What six metal aqua ions do you have to know about?

A

Fe²⁺, Cu²⁺, Co²⁺, Al³⁺, Cr³⁺ and Fe³⁺

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23
Q

In excess ammonia which metal hydroxides undergo ligands substitution?

A

Co²⁺, Cu²⁺ and Cr³⁺

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24
Q

Do metal aqua 2+ ions form weak or strong acidic solutions? And why?

A

Weak - there is only slight disassociation

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25
Q

Why are some metal hydroxides amphoteric?

A

Because some can dissolve in excess base as well as excess acid.

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26
Q

What is the equation for the reaction between cobalt aqua ions and chloride ions?

A

[Co(H₂O)₆]²⁺(aq) + 4Cl⁻(aq) ⇋ [CoCl₄]²⁻(aq) + 6H₂O(l)

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27
Q

What is the equation for the reaction between copper aqua complexes and 1,2-diaminoethane?

A

[Cu(H₂O)₆]²⁺(aq) + 3NH₂CH₂CH₂NH₂(aq) → [Cu(NH₂CH₂CH₂NH₂)₃]²⁺(aq) + 6H₂O(l)

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28
Q

What colour is [Cu(NH₃)₄(H₂O)₂]²⁺

A

Deep Blue solution

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29
Q

Are reaction with a decrease or increase in entropy more likely to happen?

A

Increase

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30
Q

What happens when transitions metals dissolve in water?

A

The water molecules form co-ordinate bonds with the metal ions, forming a metal-aqua complex.

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31
Q

What colour is [Co(H₂O)₆]²⁺

A

Pink solution

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32
Q

Give an example of a Bronsted Lowry base that is also a Lewis base.

A

Water

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33
Q

What is the overall equation for when OH⁻ are added to metal aqua +2 complexes (to the end point) ?

A

[M(H₂O)₆]²⁺(aq) + 2H₂O(l) ⇋ M(H₂O)₄(OH)₂ + 2H₃O⁺(aq)

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34
Q

What colour is [Al(H₂o)₂(OH)₄]⁻

A

Colourless solution

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35
Q

What is a Bronsted Lowry base?

A

Proton acceptor

36
Q

What is the equation for the reaction between copper aqua ions and chloride ions?

A

[Cu(H₂O)₆]²⁺(aq) + 4Cl⁻(aq) ⇋ [CuCl₄]²⁻(aq) + 6H₂O(l)

37
Q

What colour is [Fe(H₂O)₄(OH)₂]

A

Green precipitate

38
Q

How can you increase the amount of products formed in this reaction : [Co(H₂O)₆]²⁺(aq) + 4Cl⁻(aq) ⇋ [CoCl₄]²⁻(aq) + 6H₂O(l)?

A

Adding more HCl

39
Q

What colour is [Fe(H₂O)₆]³⁺

A

Yellow solution

40
Q

What colour is [CoCl₄]²⁻

A

Blue solution

41
Q

What is the equation when a metal 3+ hydroxide is in excess H⁺?

A

M(H₂O)₃(OH)₃ +3H⁺(aq) ⇋ [M(H₂O)₆]³⁺(aq)

42
Q

Is enthalpy change for ligand exchange large or small? And why?

A

Small - a similar amount of energy is required to break the bonds in the products as it is to form the bonds in the reactants.

43
Q

Which metal aqua complex undergo partial substitution of NH₃ ligands?

44
Q

What is the Lewis Theory of acids and bases based on?

A

Electron transfer

45
Q

What type of ligands are the most stable?

A

Multidentate

46
Q

What is the equation when ammonia is added to a metal aqua 2+ complex?

A

[M(H₂O)₆]²⁺(aq) + 2NH₃(aq) ⇋ [M(H₂O)₄(OH)₂(s) + 2NH₄⁺(aq)

47
Q

What colour is FeCO₃

A

Green precipitate

48
Q

What colour is Cr(H₂O)₃(OH)₃

A

Green fucking precipitate

49
Q

What colour is [Al(H₂O)₆]³⁺

A

Colourless solution

50
Q

Do metal 2+ or metal 3+ ions form more acidic solutions?

A

Metal 3+ ions

51
Q

What is the chelate effect?

A

When unidentate ligands are exchanged for multidentate ligands the complex is more stable because of the increase in entropy.

52
Q

Why do water ligands act as a Lewis base?

A

Because they are donating a pair of electrons to the metal ion.

53
Q

What is a Bronsted Lowry acid?

A

Proton donor

54
Q

What is the total charge of a metal aqua complex?

A

The charge of the metal ion.

55
Q

Other than adding OH⁻ ions how else can you form metal hydroxides from metal aqua complexes?

A

By mixing them with ammonia solution.

56
Q

What is the equation when chromium hydroxide dissolves in excess base?

A

Cr(H₂O)₃(OH)₃ + 3OH⁻(aq) ⇋ [Cr(OH)₆]³⁻(aq) + 3H₂O(l)

57
Q

In what metal aqua complexes can water ligands be exchanged for chloride ligands?

A

Cu²⁺ and Co²⁺

58
Q

What is ligand exchange?

A

Where one ligand is swapped for another.

59
Q

What is the equation for when sodium hydroxide is added to [M(H₂O)₆]³⁺(aq)

A

[M(H₂O)₆]³⁺(aq) + 3OH⁻→M(H₂O)₃(OH)₃ + 3H₂O

60
Q

In water what equilibrium equation do metal aqua +3 complexes form?

A

[M(H₂O)₆]³⁺(aq) + H₂O(l) ⇋ [M(H₂O)₅(OH)]²⁺(aq) + H₃O⁺(aq)

61
Q

What is the equation for when metal 3+ ions react with sodium carbonate?

A

2[M(H₂O)₆]²⁺(aq) + 3CO₃²⁻(aq) ⇋ 2M(H₂O)₄(OH)₂ + 3CO₂(g) + 3H₂O(l)

62
Q

What colour is [Al(H₂O)₃(OH)₃]

A

White precipitate

63
Q

What is a hydrolysis/acidity reaction?

A

The initial equilibrium set up between the metal aqua complex and the water.

64
Q

When metal 3+ aqua ions react with carbonates what will you see?

A

Bubbles of carbon dioxide.

65
Q

When do H₂O stop being substituted for OH⁻ in metal aqua complexes when OH⁻ ions are being added to the equilibrium?

A

When there is no charge and there is a precipitate.

66
Q

What colour is CuCO₃

A

Green-blue precipitate

67
Q

What colour is Fe(H₂O)₃(OH)₃

A

Brown precipitate

68
Q

What colour is [Cu(H₂O)₆]²⁺

A

Blue solution

69
Q

What is the equation for when metal 2+ ions react with sodium carbonate?

A

[M(H₂O)₆]²⁺(aq) + CO₃²⁻(aq) ⇋ MCO₃(s) + 6H₂O(l)

70
Q

What colour is [Co(H₂O)₄(OH)₂

A

Blue green precipitate

71
Q

What is the general metal-aqua complex equation for +3 metal ions?

A

[M(H₂O)₆]³⁺

72
Q

Do metal hydroxides act as Bronsted Lowry bases or acids and why?

A

Base - they can accept H+ ions

73
Q

When exchanging smaller ligands for larger is entropy change large or small? And why?

A

Large - the number of molecules is increasing.

74
Q

What is the equation when a metal 2+ hydroxide is in excess H⁺?

A

M(H₂O)₄(OH)₂ +2H⁺(aq) ⇋ [M(H₂O)₆]²⁺(aq)

75
Q

Which metal aqua complexes will the H₂O ligand fully substitute for NH₃ ligands?

A

Co²⁺ and Cr³⁺

76
Q

Do metal ions acts as a Lewis acid or base when in aqueous solution and why?

A

Lewis acid - they’re accepting a pair of electrons from the water molecules.

77
Q

What happens when you add OH⁻ to this equilibrium: [M(H₂O)₆]³⁺(aq) + H₂O(l) ⇋ [M(H₂O)₅(OH)]²⁺(aq) + H₃O⁺(aq) ?

A

The OH⁻ ions remove H₃O⁺ ions, decreasing the concentration of the products, shifting the equilibrium to the right and so producing more [M(H₂O)₅(OH)]²⁺

78
Q

What is the equation when aluminium hydroxide dissolves in excess base?

A

Al(H₂O)₃(OH)₃ + OH⁻(aq) ⇋ [Al(H₂O)₂(OH)₄]⁻(aq) + H₂O(l)

79
Q

What does amphoteric mean?

A

When something acts both as a Bronsted Lowry acid and base.

80
Q

What is the overall equation for when OH⁻ are added to metal aqua +3 complexes (to the end point) ?

A

[M(H₂O)₆]³⁺(aq) + 3H₂O(l) ⇋ M(H₂O)₃(OH)₃ + 3H₃O⁺(aq)

81
Q

Why do metal 3+ ions form more acidic solutions than metal 2+ ions (describe in 4 steps)?

A
  1. ) Metal 3+ ions have a higher charged density
  2. ) This makes them more polarising so they attract more electrons from the oxygen atoms of the co-ordinated water molecules
  3. ) Weakening the OH bond
  4. ) It is more likely that hydrogen ions will be released making them more acidic
82
Q

Why is water a Bronsted Lowry base and a Lewis base?

A

When it reacts with hydrogen to form a hydroxium ion, during this it both accepts a proton and is an electron pair donor.

83
Q

What colour is [Fe(H₂O)₆]²⁺

A

Green solution

84
Q

What is the general metal-aqua complex equation for +2 metal ions?

A

[M(H₂O)₆]²⁺

85
Q

What colour is CoCO₃

A

Pink precipitate

86
Q

What is the equation for the reaction between chromium aqua ions and excess ammonia?

A

[Cr(H₂O)₆]³⁺(aq) + 6NH₃(aq) → [Cr(NH₃)₆]³⁺(aq) + 6H₂O(l)

A2 Chemistry - Unit 5 (5 decks)

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