NCERT Class XII Chemistry
Chapter - General Principle of Process of Isolation of Elements
Questions with Solutions

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Question : 13
Total: 31
How can you separate alumina from silica in a bauxite ore associated with silica? Give equations, if any.
Solution:  
Serpeck’s process is used when silica is present in considerableamounts in bauxite ore. The ore is mixed with coke and heated at 1800°Cin presence of nitrogen, where AlN is formed.
Al2O3+3C+ N2 2 AlN+3CO
Silica is reduced to silicon which volatilises off at this temperature.
siO2+2C Si+2CO
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