Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
150 views
in Chemistry by (93.9k points)
closed by
Outline the principles of refining of metals by the following methods :
(a) Electrolytic refining
(b) Zone refining
( c) Vapour phase refining.

1 Answer

0 votes
by (91.1k points)
selected by
 
Best answer
(i) Zone refining: This method is based on the principle that the impurities are more soluble in the melt than in the solid state of the metal. A circular mobile heater is fixed at one end of the rod of the impure metal. The molten zone moves along with the heater which is moved forward. As the heater moves forward, the pure metal crystalises out of melt and the impurities pass on into the adjacent molten zone. This process is repeated several times and the heater is moved in the same direction. At one end, impurities get concentrated.
image
This method is very useful for producing semiconductor and other metals of very high purity like germanium, silicon, boron etc.
(ii) Vapour phase refining: In this method, the metal is converted into its volatile compound and collected elsewhere. It is then decomposed to give pure·metal. There are two requirements:
(i) the metal should form a volatile compound with an available reagent.
(ii) the volatile compound should be easily decomposable, so that recovery is easy.
Example : The Mond process for refining nickel is based on vapour phase refining. In this process, nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetracarbonyl `Ni+4 COoverset(330-350K)rarrunderset("Nickel tetracarbonyl")(Ni(CO)_(4))`
The carbonyl is decomposed to pure metal at high temperature.
`NI(CO)_(4)overset(450-470K)rarrNi+4CO`

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...