Titanium is a transition metal.​​ 

Titanium is extracted from titanium dioxide in a two stage industrial process.

Suggest one hazard associated with Stage 1.​​     

[1 mark]

ANSWER

Chlorine is toxic.

Water must be kept away from the reaction in Stage 2.​​ 

Give one reason why it would be hazardous if water came into contact with sodium.        

[1 mark]

ANSWER

It will undergo an exothermic reaction i.e. there will be increase in temperature. Secondly, it will produce Hydrogen gas which is very flammable.

Suggest why the reaction in Stage 2 is carried out in an atmosphere of argon and not in air.        

[2 marks]

ANSWER

Argon is unreactive and inert gas oxygen (from air) would react with sodium / titanium or water vapor (from air) would react with sodium / titanium.

Titanium chloride is a liquid at room temperature.​​ 

Explain why you would not expect titanium chloride to be a liquid at room temperature.​​         ​​ ​​ ​​ ​​​​ 

[3 marks]

ANSWER

Metal chlorides are usually ionic so metal chlorides are solid at room temperature. Hence, these ionic compounds have high melting and boiling point because of the strong attraction between the positive and negative ions which requires a lot of energy to overcome ionic force of attraction.

In Stage 2, sodium displaces titanium from titanium chloride.​​ 

Sodium atoms are oxidized to sodium ions in this reaction. Why is this oxidation reaction?​​         ​​ ​​ ​​ ​​ ​​ ​​​​ 

[1 mark]

ANSWER

Sodium atoms loses electrons therefore it is an oxidation reaction.

Complete the half equation for the oxidation reaction.​​   [1 mark]

ANSWER

Na →Na++ e-

In Stage 2, 40 kg of titanium chloride was added to 20 kg of sodium. The equation for the reaction is:

Relative atomic masses (Ar): Na = 23 Cl = 35.5 Ti = 48​​ 

Explain why titanium chloride is the limiting reactant.

You must show your working.       

[4 marks]

ANSWER

Mr of TiCl4 = 190

Moles of Na=2000023

=870 mol

Moles of TiCl4=40000190

=211 mol

Since TiCl4​​ has 211 mol. which is less than moles of Na which is 870 mol., therefore TiCl4​​ is a limiting reactant.

For a Stage 2 reaction the percentage yield was 92.3%.​​ 

The theoretical maximum mass of titanium produced in this batch was 13.5 kg. Calculate the actual mass of titanium produced.  ​​ [2 marks]

ANSWER

=92.3100

=0.923 

Actual mass=0.923×13.5

=12.5kg