Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CHEM214 > Group 4 > Flashcards

Group 4 Flashcards

1
Q

What is the cheapest reducing agent?

A

Carbon - coal, oil or charcoal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does a more electropositive metal result in for reduction?

A

More electropositive metal = more endothermic reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why can Ti not be reduced using carbon?

A

Because Ti is very a electropositive metal, whilst also forming Titanium carbide - which is hard and inert

BAD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What process is used to obtain Ti?

A

The Kroll process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What’re the steps of the Kroll process?

A

TiO2 is converted to TiCl4 using 2C and 2Cl2

TiCl4 is distilled under vacuum

TiCl4 is then reduced using even more electro+ve metal (Na) to form Ti and 4NaCl. (Mg can also be used.)
- 800 degrees
- batch reactor
- Ar atmosphere

Metal halide is washed out - recycled - giving Ti ‘sponge’
- has to be melted into ingot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What’re the uses of Ti?

A

Ti alloys used in aerospace & hi-tech sports equipment - 60% density of steel

Very corrosion resistant

Very high heat resistance - alloys don’t ‘creep’

Twice as ductile with similar tensile strength as steel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is yielded when TiCl4 is added to water?

A

TiO2 and 4HCl

Hydrolysis of TiCl4 is a violent reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of ligands does Ti(IV) prefer?

A

Hard ligands - as is a hard metal ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Are Ti(IV) complexes stable under reduction?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does dissolving TiF4 in aqueous HF yield?

A

Mainly [TiF6]2-

d0 - complex so is colourless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do Ti(IV) and V(IV) oxo-complexes differ?

A

V complexes are monomers - 1005cm-1

Ti complexes are dimers - 880cm-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the reaction of Ti(IV) halide complexes with neutral monodentate ligands in non-polar solvents?

A

1 eq gives [TiCl4L]2

2 eq gives [TiCl4L2] - cis and trans variations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why does Ti(IV) have no stereochemical preferences?

A

Because it is a d0 metal ion, and so cannot be controlled through CFT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is ‘das’?

A

It is a very good chelate ligand

Benzene ring provides a rigid backbone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

TiCl4 + 1das gives what in toluene?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

TiCl4 + 2das gives what in toluene?

A
17
Q

Whats the difference between a-TiCl3 and ß-TiCl3?

A

The a form consists of sheets of TiCl6 octahedral.

The ß form consists of single chains of TiCl6, sharing edges

The ß form converts to alpha form at ≥ 300 degrees

18
Q

What’s the use of ß-TiCl3?

A

The ß form is a catalyst for alkene polymerisation

19
Q

What type of polymer is given by polypropylene?

A

Yields ‘isotactic’ polypropylene - all Me groups oriented same way.

20
Q

Why must Ti(III) complexes be made in strict absence of oxygen?

A

So that Ti(III) is not oxidised by oxygen in air.

21
Q

What does dissolving Ti in dilute HCl give?

A

[Ti(H2O)6]3+

22
Q

What does dissolving Ti in conc HCl give?

A

Both [TiCl(H2O)5]2+ and [TiCl2(H2O)4]+ are formed

23
Q

What does dissolving Ti in very conc HCl give?

A

Ti in very concentrated HCl gives Ti(IV) complexes

24
Q

What are Ti(II) complexes rare?

A

Because Ti(II) is very strongly reducing

25
Q

What’re the 2 reasons Ti(II) chemistry has interest?

A

Organic chemistry
- Ti(II) is active in the McMurray coupling reaction

Dinitrogen chemistry
- Ti(II) reduces N-N triple bond since Ti=NR is isoelectronic with Ti=O.

26
Q

How are Zr and Hf separated, as they appear in nature together?

A

By solvent extraction or chromatography

27
Q

Why is separating Zr and Hf difficult?

A

Due to their very similar chemical properties

28
Q

How are Zr and Hf elements obtained?

A

Elements are obtained by the Kroll process - same as Ti

29
Q

What’re the uses of Zr?

A

Used as fuel cladding for nuclear fuels - has low neutron capture cross-section

Widely used as alkene polymerisation catalysts

30
Q

What use has Hf recently found?

A

As a high dielectric constant insulator layer for the gates of tiny transistors

31
Q

Is Ti(IV) chemistry similar to Zr(IV) and Hf(IV) chemistry?

A

Yes

32
Q

How can stereochemistry be dictated for group 4 M(IV) complexes?

A

Through sterics, since there is no CFSE in d0 metal ions

33
Q

What is the difference between TiCl4 / TiBr4 complexes with the Zr/Hf equivalents?

A

TiCl4 / TiBr4 complexes are tetrahedral and monomeric

ZrCl4 / ZrBr4 (and Hf) complexes are polymeric and octahedral

34
Q

What tendencies do Zr and Hf exhibit with M(II) and M(III) complexes?

A

Zr and Hf do not form M(II) complexes AT ALL

They have lower tendency to form M(III)

ALL M(III) complexes are polymeric

35
Q

How can Zr(III) complexes be diamagnetic?

A

As they are polymeric, the 2 electrons are shared between the Zr-Zr bond, as though covalent, in the same bonding orbital

Hence is diamagnetic (not magnetic)

36
Q

How are M-M bonds made more stable?

A

They are made more stable with strong field ligands

CHEM214 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions