Transition Metals Flashcards

1
Q

What is a transition metal?

A

Metals that contain an incomplete d sub shell in at least one of their ions

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2
Q

Where are transition metals found?

A

In the ‘d block’ (middle, group 3)

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3
Q

Why are Sc and Zn technically NOT transition metals, despite being found in the d block?

A

They have no or complete d shells

Sc 3+ = [Ar] Zn 2+ = [Ar] 3d10

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4
Q

What is a ligand?

A

An atom or ion which donates a lone pair to form a co-ordinate bond to metal

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5
Q

What is a complex?

A

A metal ion with ligands co-ordinately bonded to it

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6
Q

What is the co-ordination number?

A

The number of co-ordinate bonds from ligands to the metal ion in the complex

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7
Q

What is a bidentate ligand?

A

A ligand which forms two co-ordinate bonds. Two different lone pairs on the molecule donate two electron pairs

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8
Q

Give 2 examples of a monodentate ligand

A

H2O: :OH- :NH3 :CN- :Cl

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9
Q

When can optical isomerism occur?

A

Can occur when bidentate ligands are attached to an octahedral complex

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10
Q

Give an example of a multidentate ligand

A

EDTA 4-, haem, [Pt(NH3)2Cl2] (cisplatin), [Ag(NH3)2]+

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11
Q

Why is EDTA 4- such an effective ligand?

A

It has 6 lone pairs, and so can form 6 points of attachment

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12
Q

[Cu(H2O)6]2+ is added with an unknown substance. The solution turns from light blue to dark blue. What was the unknown substance?

A

Ammonia

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13
Q

Ammonia is added to [Cu(H2O)6]2+. What are the products formed?

A

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

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14
Q

Concentrated HCl is added to [Cu(H2O)6]2+. What are the products formed?

A

[CuCl4]2- + 6H2O

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15
Q

Ammonia is added to [Cu(H2O)6]2+. What is the colour change observed?

A

Light blue to dark blue

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16
Q

Concentrated HCl is added to [Cu(H2O)6]2+. What is the colour change observed?

A

Light blue to yellow

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17
Q

Concentrated HCl is added to [Cu(H2O)6]2+. The solution should turn yellow, but it looks more green. Why?

A

Because it’s going from blue to yellow

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18
Q

Ammonia is added to [Co(H2O)6]2+. What are the products formed?

A

[Co(NH3)6]2+ + 6H2O

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19
Q

Ammonia is added to [Co(H2O)6]2+. What is the colour change observed?

A

Pink to pale brown

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20
Q

Concentrated HCl is added to [Co(H2O)6]2+. What is the colour change observed?

A

Pink to dark blue

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21
Q

Concentrated HCl is added to [Co(H2O)6]2+. What are the products formed?

A

[CoCl4]2- + 6H2O

22
Q

Why is the colour change so dramatic when concentrated HCl is added to [Co(H2O)6]2+?

A

The colour change is dramatic because the co-ordination number also changes (Cl is big so can’t fit round octahedral)

23
Q

What is the chelate effect?

A

The substitution of monodentate ligands (eg H2O) by multidentate ligands

24
Q

What is a use of a chelate?

A

It is useful in dealing with heavy metal poisoning, as it ‘cages’ up and so limits the poisoning effects

25
What is the equation to work out the energy change, using Plank's constant and lamda?
Energy = hv where h = Plank's constant and lamda = the speed of light/wavelength
26
What is Plank's constant?
6.63 x10^-34 Js
27
What is the speed of light?
3x10^8 ms^-1
28
What are the factors that affect the size of energy gap?
The metal, the oxidation state, the ligands, the co-ordination number
29
Why are some substances able to give different colours/observations?
They have a variable oxidation state
30
KMnO4 is titrated against acidified Fe2+. What colour change is observed?
Colourless to pink
31
KMnO4 is used in a redox titration against acidified Fe2+. After all the acid has been used up, the colour change observed is brown/dark red rather than pink. What has happened?
There was not enough acid to full oxidise the MnO4- | Instead MnO2 formed
32
What colour is MnO4-?
Purple
33
A student is choosing an acid to acidify Fe2+ for a redox titration. The options are dilute H2SO4, conc H2SO4 and dilute HCl. Which acid should she choose? Give reasons why the others are unsuitable.
Should choose dilute H2SO4 Conc H2SO4 is an oxidising agent, but there is already an oxidising agent present Dilute HCl - Cl could be oxidised (Cl2 gas), so the titration would larger and thus inaccurate.
34
The complex ion formed in aqueous solution between cobalt (II) ions and chloride ions is a different colour from the [Co(H2O)6]2+ ion. Explain why these complexes have different colours
Ligands are different and so cause different d orbital splitting. This means different amounts of energy are required to promote electron to the next energy level and so different frequencies of light are absorbed. Therefore different wavelengths/colours of light are transmitted
35
Fill the blanks. Heterogenous catalysts reactions often involve a ____ catalyst and _____ reactants.
solid catalyst and gaseous reactants
36
Describe alternate pathway a heterogenous catalyst provides
``` Reactants adsorbed onto the surface (active sites) - weakens bonds - brings molecules closer - more favourable orientation Reaction occurs Products desorbed ```
37
What is the issue if a catalyst bonds too strongly to a reactant?
It will never let go - both the catalyst and reactant will be unable to take part in the reaction
38
What is the issue if a catalyst bonds too weakly to a reactant?
If it bonds too weakly, it will not have the desired affects.
39
What is the contact process and which catalyst does it involve?
A way of producing H2SO4 | Involves a vanadium (V) oxide catalyst
40
Give two half equations to show the contact process
SO2 + V2O5 --> V2O4 + SO3 | V2O4 + 1/2 O2 --> V2O4
41
What is catalyst poisoning?
When the catalyst is covered by a substance which blocks the active sites, thus making it ineffective
42
Fill in the blank. Homogenous catalysts are mostly involved in reactions in a _____ with a catalyst in a _______
Solution for both
43
What is an autocatalyst?
A catalyst that is also one of the products of the reaction being catalysed.
44
Give a half equation showing the reduction of manganate
MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O
45
Give two half equations to show the autocatalysis reaction of iodide ions and S2O8 2- to form iodine and sulphate ions
2I- + Fe3+ --> I2 + 2Fe3+ | S2O8 2- + 2Fe2+ --> 2SO4 2- + 2Fe3+
46
Give 2 half equations to show the reaction of MnO4- with C2O4 2-
MnO4- + 8H+ + Mn2+ --> 5Mn3+ + 4H2O | C2O4 2- + 2Mn3+ --> 2CO2 + 2Mn2+
47
Give the formula of cisplatin
[Pt(NH3)2Cl2]
48
How many lone pairs are there on EDTA 4-?
6
49
Give the formula of ethanedioate
C2O4 2-
50
Give the formula of 1,2-diaminoethane
AKA en | H2N-CH2-CH2-NH2