Question

Which process of purification is represented by the following reaction?
\[T{{i}_{(s)}}+2{{I}_{2}}_{(g)}\xrightarrow{523K}Ti{{I}_{4}}_{(g)}\xrightarrow{1700K}T{{i}_{(s)}}+2{{I}_{2}}_{(g)}\]
(A)zone refining
(B)mond’s process
(C) Cupellation
(D)van arkel process

Answer 1

Hint: The question is asking about the purification of Ti. Ti is a transition metal and transition metals show different properties. It is also a two-step purification process.

Complete answer:
Let’s take a look at the options.
-Zone refining method is used for the purification of semiconductors. In this a zone of semi-molten impure metal is passed slowly. Because of this the impurities and pure metal having different melting and soluble properties get separated. So OPTION (A) is incorrect.
-Mond’s process involves CO for the purification of Ni to give nickel carbonyl. No other element gives a carbonyl under mild condition. So OPTION (B) is incorrect.
-Cupellation process of purification is used to purify noble metals (gold, silver). The impure metal is heated at a very high temperature. The pure metal gets separated and the impurities react and come out as slag. So OPTION (C) is incorrect
-In Van arkel method Ti is heated in an iodine chamber. It gets converted into titanium iodide and then it is again heated at a very high temperature to decompose into pure Ti back. Ti is a transition metal and easily forms complexes in vapour state.
So, we are now sure why OPTION A, B, C are incorrect.
Therefore, Ti is purified by the process of Van arkel Method.
So, OPTION (D) is the correct answer.

Note: While answering questions from purification of metals, you must remember the definitions. You can get confused between Mond’s process and van arkel method because both are two step processes.