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Date May 2017 Marks available 1 Reference code 17M.2.sl.TZ1.2
Level SL Paper 2 Time zone TZ1
Command term State Question number 2 Adapted from N/A

Question

Titanium is a transition metal.

TiCl4 reacts with water and the resulting titanium(IV) oxide can be used as a smoke screen.

Describe the bonding in metals.

[2]
a.

Titanium exists as several isotopes. The mass spectrum of a sample of titanium gave the following data:

Calculate the relative atomic mass of titanium to two decimal places.

[2]
b.

State the number of protons, neutrons and electrons in the \({}_{22}^{48}{\text{Ti}}\) atom.

[1]
c.

State the full electron configuration of the \({}_{22}^{48}{\text{Ti}}\)2+ ion.

[1]
d.i.

Explain why an aluminium-titanium alloy is harder than pure aluminium.

[2]
d.ii.

State the type of bonding in potassium chloride which melts at 1043 K.

[1]
e.i.

A chloride of titanium, TiCl4, melts at 248 K. Suggest why the melting point is so much lower than that of KCl.

[1]
e.ii.

Formulate an equation for this reaction.

[2]
f.i.

Suggest one disadvantage of using this smoke in an enclosed space.

[1]
f.ii.

Markscheme

electrostatic attraction

between «a lattice of» metal/positive ions/cations AND «a sea of» delocalized electrons

 

Accept mobile electrons.

Do not accept “metal atoms/nuclei”.

[2 marks]

a.

\(\frac{{(46 \times 7.98) + (47 \times 7.32) + (48 \times 73.99) + (49 \times 5.46) + (50 \times 5.25)}}{{100}}\)

= 47.93

 

Answer must have two decimal places with a value from 47.90 to 48.00.

Award [2] for correct final answer.

Award [0] for 47.87 (data booklet value).

[2 marks]

b.

Protons: 22 AND Neutrons: 26 AND Electrons: 22

[1 mark]

c.

 

1s22s22p63s23p63d2

[1 mark]

d.i.

titanium atoms/ions distort the regular arrangement of atoms/ions
OR
titanium atoms/ions are a different size to aluminium «atoms/ions» 

prevent layers sliding over each other

 

Accept diagram showing different sizes of atoms/ions.

[2 marks]

d.ii.

ionic
OR
«electrostatic» attraction between oppositely charged ions

[1 mark]

e.i.

«simple» molecular structure
OR
weak«er» intermolecular bonds
OR
weak«er» bonds between molecules

 

Accept specific examples of weak bonds such as London/dispersion and van der Waals.

Do not accept “covalent”.

[1 mark]

e.ii.

TiCl4(l) + 2H2O(l) → TiO2(s) + 4HCl(aq)

correct products

correct balancing

 

Accept ionic equation.

Award M2 if products are HCl and a compound of Ti and O.

[2 marks]

f.i.

HCl causes breathing/respiratory problems
OR
HCl is an irritant
OR
HCl is toxic
OR
HCl has acidic vapour
OR
HCl is corrosive

 

Accept “TiO2 causes breathing problems/is an irritant”.

Accept “harmful” for both HCl and TiO2.

Accept “smoke is asphyxiant”.

[1 mark]

f.ii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.i.
[N/A]
d.ii.
[N/A]
e.i.
[N/A]
e.ii.
[N/A]
f.i.
[N/A]
f.ii.

Syllabus sections

Core » Topic 2: Atomic structure » 2.1 The nuclear atom
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