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A level Chemistry > Unit 3.4 - Chemistry of the d-block transition metals > Flashcards

Unit 3.4 - Chemistry of the d-block transition metals Flashcards

1
Q

What are all of the elements from scandium to zinc? What does this mean?

A

d-block elements
3d orbitals are being filled

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2
Q

Transition metal

A

An element that possess a partially filled d sub-shell as an atom or in its stable ions

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3
Q

Why are scandium and zinc not transition metals even though they’re d-block elements?

A

Scandium: 3d orbital is empty
Zinc: 3d orbital is full
So neither are partially full, which is the definition of a transition metal

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4
Q

Which d-block elements are NOT transition metals?

A

Scandium and zinc

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5
Q

Which level fills first, the 4s or 3d level?

A

4s level fills first

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6
Q

Which orbital has the lowest amount of energy as the 3d level fills?

A

The energy of the 3d electrons is below that of the 4s electrons

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7
Q

Which level are electrons removed from first and then afterwards when electrons are removed from scandium and zinc?

A

They’re removed first from the 4s level, and only then from the 3d level

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8
Q

Where do we remove electrons from first in the transition elements and then afterwards when forming ions?

A

We remove the 4s electrons first, then the 3d electrons in the reverse order to that in which we filled them

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9
Q

Cr3+ electronic configuration

A

1s^22s^22p^6s3^23p^63d^3

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10
Q

General properties of the transition element

A
  1. Metals with closely packed structures
  2. Atomic radius decreases gradually = first ionisation energy increases gradually
  3. Strong metallic bonds = high melting points
  4. High densities + high tensile strengths
  5. Form alloys with one another readily
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11
Q

How come transition elements are dense?

A

Closely packed structures

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12
Q

Why does the first ionisation energy of the transition elements increase gradually?

A

As the atomic radius decreases gradually

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13
Q

Why do the transition elements form strong metallic bonds?

A

As the 3d and 4s electrons are available for metallic bonding

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14
Q

Why do the transition elements have high melting points?

A

Strong metallic bonds

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15
Q

Why do the transition elements have high densities and high tensile strengths?

A

Have relatively small atomic radii and closely packed structures

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16
Q

Why do the transition elements form alloys with one another readily?

A

As they have similar atomic radii

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17
Q

Why does having similar atomic radii in transition elements mean that they can form alloys with one another readily?

A

Because there will be little disruption to the metal lattice when one atom is substitute for another

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18
Q

Example of an alloy

A

Stainless steel

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19
Q

What makes up stainless steel?

A

Fe/Cr

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20
Q

What’s good about stainless steel and why is this the case?

A

Rusts slowly due to the chromium element

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21
Q

Characteristic properties of the transition elements

A
  1. Variable oxidation states
  2. Catalysis
  3. Complex ion formation
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22
Q

How many oxidation states can transition elements occur in in their compounds?

A

Two or more

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23
Q

Most common oxidation states of transition elements

A

+2, +3

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24
Q

Why do the transition elements have varying oxidation states?

A

The difference in energy between the 3d and the 4s electrons is relatively small (i.e - the ionisation energies of the 3d and 4s electrons are similar)

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25
Q

When do chromium and manganese form compounds in their highest oxidation states?

A

With oxygen and fluorine

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26
Q

Which elements can have the electronic structure of Argon and when does this occur?

A

Chromium and manganese form compounds in their highest oxidation states with oxygen and fluorine
They have the electronic structure of argon in these states

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27
Q

Which transition elements compounds form compounds in the highest oxidation states?

A

Chromium and manganese

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28
Q

What has happened to Cr6+ and Mn7+ for them to have the same electronic structure as argon?

A

Remove all of their electrons

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29
Q

Catalysts

A

Substances that increase the rate of a chemical reaction by providing an all active pathway with a lower activation energy

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30
Q

How do catalysts increase the rate of a chemical reaction?

A

By proving an alternative pathway with a lower activation energy

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31
Q

Why is the position of equilibrium unaffected with catalysts and what is the only thing that is affected?

A

The activation of both the forward and backward reaction are reduced
Only rate is affected

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32
Q

Why are catalysts so important in industry?

A

Reactions occur faster
Provides chemical reactions at lower temperatures = lowers the energy demand of a reaction

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33
Q

What are transition metals and their compounds important as?

A

Industrial catalysts

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34
Q

What type of catalysts do transition elements act as and how?

A

Surface catalysts
Provide active sites on their surface to facilitate the reaction

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35
Q

How come transition elements can act as surface catalysts that provide active sites on their surfaces?

A

As they have partially filled d-orbitals high enable them to form temporary bonds with reactant molecules

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36
Q

When is vanadium used as a catalyst?

A

Contact process = manufacture of sulphuric acid

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37
Q

When is iron used as a catalyst and in what state?

A

Fe/FeO
Haber process = manufacture of ammonia

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38
Q

When is nickel used as a catalyst?

A

Hydrogenation of C=C bonds in vegetable oils

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39
Q

Catalyst of the Haber process (manufacture of sulphuric acid)

A

Vanadium

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40
Q

Catalyst of the haber process

A

Iron Fe/FeO

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41
Q

Catalyst of the hydrogenation of C=C bonds in vegetable oils

A

Nickel

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42
Q

What is sulphuric acid used for in industry?

A

Car batteries

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43
Q

What is ammonia used for in industry?

A

Fertiliser

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44
Q

What are vegetable oils used for in industry?

A

To make margarine

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45
Q

Why can the transition elements act as catalysts in solution?

A

Because the transition metal may take part in a sequence of reaction stages and be left unchanged because of its ability to have more than one oxidation state

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46
Q

What can transition elements do due to their ability to have more than one oxidation state? Why?

A

Can act as catalysts in solution
May are part in a sequence of reaction stages and be left unchanged

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47
Q

Why isn’t it sustainable to use transition metals as catalysts and what is being done instead?

A

They have to be mined
Enzymes are being designed to take part in industrial processes instead

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48
Q

Area under a Maxwell-Boltzmann distribution

A

Area under the curve = total number of particles with specific energies

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49
Q

How do transition metals change oxidation states?

A

By gaining or losing electrons in d-orbitals

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50
Q

How can transition metals specifically speed up reactions?

A

By speeding up the transfer of electrons in d-orbitals

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51
Q

How do reactants react with transition elements when they act as catalysts?

A

Use vacant d-orbitals to form temporary bonds with catalyst which holds the reactant so that the reaction can take place

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52
Q

heterogeneous catalyst

A

A catalyst in a different physical state to the reactants

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53
Q

Homogenous catalyst

A

A catalyst in the same physical state to the reactants

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54
Q

Example of a heterogenous catalyst

A

Fe in the haber process

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55
Q

Example of a homogenous catalyst

A

Concentrated H2SO4 in esterification = all liquid

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56
Q

Zn2+ electronic structure

A

1s^22s^2sp^63s^23p^63d^10

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57
Q

Catalyst of Haber process

A

Iron

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58
Q

Catalyst of hydrogenation of oils/alkenes to form margarines

A

Nickel

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59
Q

Catalyst of polymerisation of ethane

A

Iron, cobalt

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60
Q

Catalyst of contact process

A

Vanadium (V) oxide

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61
Q

Haber process equation

A

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

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62
Q

Polymerisation of ethane reaction

A

nCH2 = CH2 + H2 —> [-CH2-CH2-]n

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63
Q

Vanadium (V) oxide

A

V2O5

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64
Q

Contact process reaction

A

2SO2 + O2 —> 2SO3

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65
Q

Catalyst of production of nitric acid from ammonia

A

Platinum

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66
Q

Catalyst of the decomposition of hydrogen periodise

A

Manganese (IV) oxide

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67
Q

Decomposition of hydrogen perioxide reaction

A

2H2O2 —> 2H2O + O2

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68
Q

Reactions for the production of nitric acid from ammonia

A

4Nh3 + SO2 —> 4NO + 6H2O
2NO + O2 —> 2NO2 ⇌ N2O4
3NO2 + H2O —> 2HNO3 + NO

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69
Q

What is a complex ion?

A

Complexes are made up of a transition metal ion bonded to atoms or molecules which surround it (ligands)

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70
Q

What do ligands do with transition metal ions?

A

Form coordinate bonds/dative bonds

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71
Q

How are complex ions always written?

A

In square brackets

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72
Q

What do complex ions mostly have but not always?

A

Charges

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73
Q

Describe how a coordinate bond is formed between a transition metal ion and a ligand to form a complex ion

A

The transition metal has an empty orbital, and the ligand has a lone pair of electrons
The two atomic orbitals overlap to form a molecular orbital
A coorinate bond is formed between the ligand and the transition metal ion

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74
Q

Ligand

A

A small molecule or ion with a lone pair of electrons that can form a coordinate bond to a transition metal

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75
Q

Common ligands

A

H2O, NH3, Cl-, OH-, CN-

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76
Q

Complex

A

The combination of a transition metal ion and the ligands

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77
Q

Most common way of ligands being arranged around a transition metal ion

A

6 ligands arranges octahedral around the metal atom

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78
Q

Less common way of ligands being arranged around a transition metal ion

A

4 ligands arranged tetrahedrally

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79
Q

Angle in octahedrally arranged ligands around a metal atom

A

90

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80
Q

Angle in tetrahedrally arranged ligands around the metal atom

A

109.5

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81
Q

Which transition metal can be used to demonstrate the variation in transition metal complexesL

A

Copper

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82
Q

Which copper complexes are used to demonstrate the variation in transition metal complexes?

A

[Cu(H2O)6]2+
[CuCl4]2-
[Cu(H2O)2(NH3)4]^2+

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83
Q

Why are the structures and pooper ties of different copper complexes different even though they all contain Cu2+ ions?

A

Due to their different ligands

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84
Q

What are the most common complexes of aqueous solution of Cu2+ or Co2+?

A

[Cu(H2O)6]2+ and [Co(H2O)6]2-

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85
Q

Where do we draw the coorinate bond from in H2O and why?

A

From the oxygen
The lone pair of electrons is on the oxygen

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86
Q

How is the complex [Cu(H2O)2(NH3)4]2+ formed?

A

Addition of ammonia to a solution containing [Cu(H2O)6]2+ causes ammonia molecules to replace 2 water molecules

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87
Q

[Cu(H2O)2(NH3)4]2+ colour

A

Royal blue solution containing the ions

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88
Q

Shape of the [Cu(H2O)2(NH3)4]2+ complex

A

Octahedral, but as it contains 2 different ligands, there could be two different arrangements of ligands

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89
Q

Shape of [CuCl4]2- complexes

A

Tetrahedral
All 4 chlorides at 109.5 to each other

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90
Q

How are [CuCl4]2- complexes formed?

A

When copper (II) ions react with concentrated hydrochloric acid, which displaces water molecules

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91
Q

Why does a distinct colour change occur when [CuCl4]2- complexes are formedL

A

As the change in ligands and coordination geometry both contribute to changes in light absorbed

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92
Q

Steps to naming com0exes

A
  1. State the number of ligands around the central atom
  2. Name the ligands present
  3. Name the cation
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93
Q

Word used for the number of ligands around the central atom, from 1 to 6

A

Mono
Di
Tri
Tetra
Penta
Hexa

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94
Q

Name for H2O ligand

A

Aqua

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95
Q

Name for NH3 ligand

A

Ammine

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96
Q

Name for OH- ligand

A

Hydroxy

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97
Q

Name for CN- ligand

A

Cyano

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98
Q

Name for Cl- ligand

A

Chloro

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99
Q

How do we name the cation in a complex if we have a neutral or cationionic (positive) complex?

A

Use the ordinary name of the metal (e.g - iron, copper)

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100
Q

How do we name the cation in a complex if we have an anionic (negative) complex?

A

Use the latinised name

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101
Q

Cr latinised name

A

Chromate

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102
Q

Fe latinised name

A

Ferrate

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103
Q

Zinc latinised name

A

Zincate

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104
Q

Pb latinised name

A

Plumbate

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105
Q

Mn latinised name

A

Manganate

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106
Q

Cu latinised name

A

Cuprate

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107
Q

Al latinised name

A

Aluminate

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108
Q

Sn latinised name

A

Stannate

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109
Q

Co latinised name

A

Cobaltate

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110
Q

Name for complex [Fe(CN)6]4-

A

Hexacyanoferrate (II)

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111
Q

Name and state where 3 transition metals are found as trace element in living systems

A

Iron = haemoglobin
Cobalt = spleen
Manganese = photosystems in photosynthesis

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112
Q

Name 3 important economic uses of transition metals

A

Catalysts
Fe = in the haber process to make ammonia
Iron = in the construction industry (steel)

113
Q

How are most of the complex ions formed by transition metal ions?

A

Coloured

114
Q

In what state only are transition metal atoms coloured and why?

A

In complexes
Ligands cause the colours

115
Q

What cause the colour in transition metal complexes?

A

Ligands

116
Q

[Cr(H2O)6]3+ colour

A

Dark green

117
Q

[Fe(H2O)6]2+ colour

A

Pale green

118
Q

[Fe(H2O)6]3+ colour

A

Yellow

119
Q

[Cu(H2O)6]2+ colour

A

Bright blue

120
Q

[Co(H2O)6]2+ colour

A

Pink

121
Q

[CoCl4]2- colour

A

Blue

122
Q

[CuCl4]2- colour

A

Yellow or green

123
Q

Colour of an aqueous solution of compounds containing the ions Cr3+

A

Green

124
Q

Colour of an aqueous solution of compounds containing the ions Co2+

A

Pink

125
Q

Colour of an aqueous solution of compounds containing the ions Fe2+

A

Green

126
Q

Colour of an aqueous solution of compounds containing the ions Fe3+

A

Yellow

127
Q

Colour of an aqueous solution of compounds containing the ions Cu2+

A

Blue

128
Q

Colour of an aqueous solution of compounds containing the ions CrO4^2-

A

Yellow

129
Q

Colour of an aqueous solution of compounds containing the ions Cr2O7^2-

A

Orange

130
Q

Colour of an aqueous solution of compounds containing the ions MnO4-

A

Purple

131
Q

What colour is a transition metal complex without ligands?

A

Colourless

132
Q

Why are Cu2+ complexes blue?

A

If white light (ordinary sunlight for example) passes through copper (II) sulphate solution, some wavelengths of light are absorbed by the solution.
Copper (II ions in solution absorb light in the red region of the spectrum
The light which passes through the solution and out of the other side will have all of the colours except for red
We see this mixture of wavelengths as pale blue (cyan)
It’s the blue light that’s transmitted that we can see

133
Q

[Cu(H2O)6]2+
[CuCl4]2-
[Cu(h2O)2(NH3)4]2+
colours

A

blue
green
deep blue

134
Q

what do different ligands in a complex ion cause?

A

different colours

135
Q

hexa (6 coordinate bonds) complexes shape

A

oxtehedral

136
Q

tetra (4 coorinate bonds) complexes shape

A

tetrahedral

137
Q

what do ligand have a dramatic effect on when introduced around a metal ion?

A

on the orbitals of the atom

138
Q

describe the orbitals of a transition metal without ligands

A

5 degenerate 3d orbitals with the same energy

139
Q

how many types of d orbital are there?

A

5

140
Q

what raises the energy of the d orbitals when ligands bond with a transition metal ion?

A

the repulsion between the electrons in the ligands and the electrons in the d orbitals of the metal ion

141
Q

why don’t the energies of the d orbitals raise by the same amount when when ligands bond with a transition metal ion?

A

because of the way the d orbitals are arranged in space

142
Q

ways the d orbitals are split in octehedrals when ligands bond with the transition metal ion

A

2 d orbitals above (higher energy)
3 d orbitals below (lower energy)

143
Q

ways the d orbitals are split in tetrahedrals when ligands bond with the transition metal ion

A

3 d oribitals above (higher energy)
2 d orbitals below (lower energy)

144
Q

what does the size of the energy gap between the 2 split groups when ligands bond with a transition metal ion vary with?

A

the nature of the transition metal ion
its oxidation state
the nature of the ligands

145
Q

what happens when white light is passed through a solution of ions?

A

some of the energy in the light is used to promote an electron from the lower set of orbitals into a space in the upper set

146
Q

what does the presence of water molecules in hydrated copper (II) sulphate cause?

A

the splitting of d orbitals

147
Q

describe the 3d orbitals of the Cu2+ ion before water is added

A

degenerate 3d orbitals

148
Q

what happens to the orbitals of Cu2+ when water is added?

A

they split

149
Q

what happens to blue light when passed through copper (II) sulfate solution?

A

is the only light that’s transmitted

150
Q

what does white light cause in the split d orbitals of a metal ion complex?

A

a transition between the lower split level and the higher split level
an electron is promoted to the higher level and the frequency left behind is the colour seen

151
Q

why does the compled [Cu(H2O)6]2+ appear blue?

A
  1. the water ligands cause the d-orbitals to split into 3 of lower energy and two of higher energy
  2. electrons can move from the lower to higher energy level by absorbing a specific frequency of light
  3. this corresponds to the energy gap E=hf
  4. the light that isn’t absorbed is the colour that is seen
  5. therefore it appears blue as it absorbs all other colours apart from blue
152
Q

equation for calculating the energy of 1 electron transmission

A

e=hf

or

E = hc/lambda

153
Q

what do we need wavelength in?

A

metres

154
Q

how do we go from J to kJmol-1?

A

divide by 1000
multiply by avogadro constant

155
Q

why are some complexes colourless? give examples

A

copper complexes have an electronic configuration with a full d-sub shell (d10) which mains there is no empty orbitals to allow electrons to jump between energy levels (nowehere for electrons to go when the d orbitals split)
So, Cu (I) complexes do not absorb light in the visible region and appear colourless
Zn2+ is also colourless for the same reason

also Sc3+ is colourless
is has an empty d subshell, so there’s no electrons to move between d orbitals

156
Q

ions in complexes that cause them to be colourless

A

Cu (I)
Zn2+
Sc3+

157
Q

colour of [Cu(H2O)6]2+

A

cyan/pale blue

158
Q

how is [Cu(H2O)6]2+ formed from copper oxide and sulphuric acid?

A

neutralisation reaction
yields water
water can bind to copper to form [Cu(H2O)6]2+
cyan/pale blue colour appears

159
Q

what can [Cu(H2O)6]2+ be formed from reacting?

A

copper oxide
sulphuric acid

160
Q

Summarise why some complexes a colourless

A

Nowhere for electrons to go when absorbing frequencies of light in the visible region

161
Q

Name 3 colourless complexes

A

Cu (I)
Zn (II)
Sc3+

162
Q

Describe copper

A

Brownish-red metallic element

163
Q

Why is copper so important? Give an example

A

One of the most widely used metals
(e.g - electrical wires)

164
Q

Why is copper used for electrical wires?

A

Excellent conductor of electricity

165
Q

Describe pure copper

A

Soft

166
Q

What is pure copper good for and why?

A

Copper piping
Soft

167
Q

How are alloys of copper different to pure copper?

A

Far harder and stronger

168
Q

Two most important alloys of copper

A

Brass
Bronze

169
Q

Brass alloy

A

Zinc and copper

170
Q

Bronze alloy

A

Tin and copper

171
Q

What do alloys of copper and pure copper have in common?

A

The alloys have corrosion resistance almost as goof as t\hat of pure copper

172
Q

Which electron is lost first in transition metal ions?

A

4s electron

173
Q

Describe copper (I) compounds

A

Not very stable

174
Q

What can easily be oxidised to copper (II) and why?

A

Copper (I) compounds
Not very stable

175
Q

What can copper (I) compounds be oxidised to and how?

A

To copper (II)
In many cases, by mere exposure to air

176
Q

What are copper (I) compounds mostly?

A

Unstable

177
Q

What can copper (I) compounds be formed as? Give an example

A

Insoluble compounds
e.g - copper (I) iodide, a white solid

178
Q

Describe copper (I) iodide

A

White solid

179
Q

How do copper (II) ion exist?

A

Not as simple ions in aqueous solution but as complex hydrated ions

180
Q

Main copper complex ion present in aqueous solution

A

Hexaqua copper (II)
[Cu(H2O)6]^2+

181
Q

Colour of [Cu(H2O)6]^2+

A

Blue

182
Q

Different reactions of copper (II) ions to remember

A

With iodine ions
With aqueous sodium hydroxide
Ligand exchange reactions (aqueous ammonia and concentrated hydrochloric acid)

183
Q

Example reaction for the reaction between copper (II) ions with iodide ions

A

Aqueous copper (II) sulfate and potassium iodide

184
Q

What happens in the reaction between aqueous copper (II) sulfate and potassium iodide?

A

Copper (II) ions a reduced to copper (I) ions

185
Q

What happens in the reaction between aqueous copper (II) sulfate and potassium iodide to the iodine?

A

Iodide ions are oxidised to iodine

186
Q

How is copper (I) iodide formed?

A

As a white precipitate

187
Q

What is the red-brown solution formed when copper (II) ions react with iodide ions?

A

Due to the iodine which reacts with excess iodide ions to form the soluble complex ion, I3-

188
Q

What are the two colours formed during the reaction of copper (II) ions and iodide ions and why does this occur?

A

Copper (I) iodide is formed as a white precipitate
The red-brown solution is due to he iodine, which reacts with excess iodide ions to form the soluble complex ion, I3-

189
Q

Equation for the reaction between copper (ii) ions and iodide ions

A

2Cu2+ + 4I- —> 2CuI + I2

190
Q

What type of reaction is the reaction between copper (II) ions and iodide ions?

A

Redox

191
Q

What do metallic cations normally act as in redox reactions?

A

Oxidising agents

192
Q

What happens to iodide ions in the reaction between copper (II) ions and iodide ions?

A

Oxidised to iodine

193
Q

What happens when sodium hydroxide and copper (II) ions are reacted in aqueous solution?

A

Gelatinous blue precipitate of copper (II) hydroxide is formed

194
Q

When is a gelatinous precipitate of copper (II) hydroxide formed?

A

When sodium hydroxide and copper (II) ions react in aqueous solution

195
Q

How do we know that copper (II) hydroxide is a basic hydroxide?

A

Precipitate is insoluble in excess alkali

196
Q

What kind of hydroxide is copper (II) hydroxide?

A

Basic

197
Q

What give experimental evidence that copper (II) hydroxide is a basic hydroxide?

A

Insoluble in excess alkali
Reacts with an acid to form a copper (II) salt

198
Q

Equation for the reaction between copper (II) ions and aqueous sodium hydroxide

A

Cu2+ + 2OH- —> Cu(OH)2

199
Q

What happens when a transition metal ion is exposed to a mixture of ligands?

A

Ligands can be exchanged to form a new complex

200
Q

Example of a mixture of ligands

A

An aqueous solution containing chloride ion

201
Q

Wha kind of processes are ligand exchange reactions?

A

Equilibrium processes

202
Q

Why is knowing the concentration of metal ions and any possible ligands key to identifying the species that will be present in solution in ligand exchange reactions?

A

They’re equilibrium processes

203
Q

What do processes being equilibrium processes allow us to do?

A

Identify the species that will be present in solution

204
Q

What can we do with equilibrium processes?

A

Manipulate the side of the equilibrium point

205
Q

What happens when the side of the equilibrium point is changes?

A

The colour alters

206
Q

What is ammonia?

A

A weak alkali

207
Q

What does ammonia solution contain and why?

A

Hydroxide ions
Ammonia is a weak alkali

208
Q

What happens when concentrated ammonia solution is added to copper (II) ions in aqueous solution?

A

A blue precipitate of copper (II) hydroxide is initially formed

209
Q

What happens when excess ammonia is added to copper (II) ions in aqueous solution?

A

A deep blue/royal blue solution is formed

210
Q

Why is a deep blue solution formed when excess ammonia is added to copper (II) ions?

A

The ammonia molecules have complexed with the copper (II) ions

211
Q

How much ammonia is added to copper (II) ions to form a blue precipitate?

A

Just a few drops

212
Q

Describe the deep blue solution formed when excess ammonia reacts with copper (II) ions

A

Completely soluble

213
Q

Equation for the reaction between copper (II) ions and ammonia

A

[Cu(H2O)6]^2+ + 4NH3 ⇌ [Cu(H2O)2(NH3)4]^2+ +2H2O
(Remember, it’s the complex ion that takes place here)

214
Q

[Cu(H2O)6]^2+ name

A

Hexaqua copper (II)

215
Q

[Cu(H2O)6]^2+ colour

A

Blue

216
Q

[Cu(H2O)2(NH3)4]^2+ name

A

Diaqua tetramine copper (II)

217
Q

[Cu(H2O)2(NH3)4]^2+ colour

A

Deep blue

218
Q

Why is the reaction between copper (II) ions and ammonia an exchange reaction?

A

4 ammonia ligands replace 4 water ligands

219
Q

Why is hydrochloric chosen to react with copper (II) ions?

A

A good source of chloride ions

220
Q

What type of hydrochloric acid has to be added to copper (II) ions?

A

Concentrated

221
Q

What happens when concentrated hydrochloric acid is added to copper (II) ions in exces?

A

Yellow-green solution is formed

222
Q

Why is the reaction between hydrochloric acid and copper (II) ions an exchange reaction?

A

The water molecules have been replaced by chloride ions

223
Q

Equation for the reaction between copper (II) ions and hydrochloric acid

A

[Cu(H2O)6]^2+ + 4Cl- ⇌ [CuCl4]^2- + 6H2O

224
Q

[CuCl4]^2- name

A

Tetrachloro cuprate (II)

225
Q

[CuCL4]^2- colour

A

Yellow-green

226
Q

What are the two things that have swapped in the exchange reaction between copper (II) ions and hydrochloric acid?

A

Ligands
Geometry

227
Q

How has geometry been swapped during the reaction between copper (II) ions and hydrochloric acid?

A

Octahedral to tetrahedral structure

228
Q

What happens if we add water back to the reaction between concentrated sulphuric acid and copper (II) ions? Why?

A

Colour turns back blue
The position of equilibrium has shifted to the left

229
Q

Why isn’t the blue colour as strong when you add water back to the reaction between concentrated hydrochloric acid and copper (II)?

A

Due to the dilution effect

230
Q

Le Chatelier’s principle

A

When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change

231
Q

What happens to the position of equilibrium if the concentration is increased on one side of an equation?

A

The position of equilibrium moves to the other side

232
Q

What happens to the position of equilibrium if pressure is increased?

A

Position of equilibrium moves to the side of the equation with the least gaseous molecules (look at big numbers in front) and vice versa

233
Q

What type of reactions does changing the pressure affect?

A

Reactions where gases are involved

234
Q

What happens to the position of equilibrium if we add a catalyst and why?

A

Speeds up the rate of the forward and reverse reactions equally, so no effect on the position of equilibrium
(Although the state of equilibrium is established more quickly)

235
Q

What happens to the position of equilibrium if we increase the temperature?

A

Equilibrium position moved in the endothermic (positive) direction (absorb the extra heat) and vice versa

236
Q

Describe chromium

A

Grey
Metallic
Can take on a high polish
One of the transition elements

237
Q

What are the oxidation states that chromium exists in?

A

+2
+3
+6

238
Q

Describe the +2 oxidation state of chromium

A

Unstable in air

239
Q

Describe the +3 oxidation state of chromium

A

Most stable state of chromium

240
Q

Describe the +6 oxidation state of chromium

A

Found mainly with very electronegative elements such as oxygen

241
Q

Examples where chromium is found with a +6 oxidation state?

A

Dichromate (VI)
Chromate (VI)

242
Q

What is the dichromate (VI) ion in equilibrium with?

A

The chromate (VI) ion

243
Q

How does chromate (VI) change into dichromate (VI)?

A

By adding acid

244
Q

What happens when you add acid to chromate (VI)?

A

Changes into dichromate (VI)

245
Q

How do you turn dichromate (VI) into chromate (VI)?

A

By adding alkali

246
Q

What happens when you add alkali to dichromate (VI)?

A

Turns into chromate (VI)

247
Q

Does the reaction of turning into dichromate (VI) from chromate (VI) and vice versa involve redox?

A

No

248
Q

Equation of the reaction for the conversion of chromate (VI) into dichromate (VI)

A

2CrO4^2- + 2H+ (equilibrium) Cr2O7^2- + H2O

249
Q

Colour of chromate (VI) ion

A

Yellow

250
Q

Colour of dichromate (VI) ion

A

Orange

251
Q

What is the dichromate (VI) ion in acidic solution?

A

A powerful oxidising agent

252
Q

What happens when dichromate (VI) ions react with acidic solution?

A

Dichromate (VI) ions are reduced to chromium (III) ions

253
Q

Two species which are readily oxidised by dichromate (VI) ions

A

1.) iron (II) ions
Fe^2+ —> Fe^3+

2.) ethanol
CH3CH2OH —> CH3CHO

254
Q

Chromium (III) ions colour

A

Green

255
Q

What’s the colour change when iron (II) ions are oxidised by dichromate (VI) ions?

A

The colour change is difficult to see owing to the formation of yellow iron (III) ions

256
Q

Fe3+ ions colour

A

Yellow

257
Q

Half equation for the reduction of the dichromate (VI) ion

A

Cr2O7^2- + 14H+ + 6e- —> 2Cr^3+ + 7H2O

258
Q

Combine the half equation for the oxidation of iron (II) ions and the \oxidation of Fe2+ ions

A

Cr2O7^2- + 14H+ + 6e- —> 2Cr^3+ + 7H2O
Fe^2+ —> Fe^3+ + e- (x6)

Cr2O7^2- + 14H+ + 6Fe^2+ —> 2Cr^3+ + 6Fe^3+ + 7H2O

259
Q

How do chromium (III) ions exist?

A

Not as simple ions in aqueous solution but as complex hydrated ions

260
Q

Main complex ion present in aqueous solution

A

[Cr(H2O)6]^3+

261
Q

[Cr(H2O)6]^3+ name

A

Hexaqua chromium (III)

262
Q

With what type of ions does adding an excess of OH- dissolve the initial precipitate? Give an example

A

Amphoteric
e.g - Cr^3+ ions

263
Q

Dichromate ion

A

Cr2O7^2-

264
Q

Chromate ion

A

CrO4^2-

265
Q

Example of a transition metal having variable oxidation states

A

Mn
+1 to +7

266
Q

Why is copper a transition metal?

A

Copper atoms can form Cu2+ cations, which have incomplete d subshells

267
Q

What do we mention when asked to give 3 properties of the d- block?

A
  • form coloured ions
  • catalysts
  • variable oxidation states
268
Q

How could iron (III) oxide be chemically separated from aluminium oxide?

A

All aqueous NaOH, Al2O3 dissolves whilst Fe2O3 doesn’t
Filter off undissolved Fe2O3

269
Q

Acid

A

Species that can donate a proton or accept an electron pair

270
Q

Base

A

Species that can accept a proton or donate an electron pair

271
Q

What makes an acid or base strong?

A

Completely ionised

272
Q

What makes an acid or base weak?

A

Partially ionised

273
Q

Why can transition metal complexes act as catalysts?

A

-variable oxidation states
-partially filled d-orbitals which enable them to form temporary bonds with the reactant molecules

274
Q

Precipitate formed with NaOH and Mg2+ or Pb2+

A

White

275
Q

What happens when acids react with metal carbonates?

A

Gives CO2 gas

276
Q

Grams in 1dm3

A

1000g

277
Q

How many dm3 is 1000g?

A

1

278
Q

How do we find an appropriate wavelength to find the concentration of something in an equilibrium mixture?

A

Find a wavelength absorbed by one but not the other

A level Chemistry (39 decks)

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