91Ó°ÊÓ

A rock that constitutes of silicate groups and is accountable for making 90% of the earth’s crust is called a silicate rock. Its application includes the manufacturing of ceramics, abrasives, and glass.

(a) A chemical way of removing the \({\rm{Si}}{{\rm{O}}_2}\) from the surface of the object would be by the dissolution of the silica. The only acid in which silica is soluble is hydrofluoric acid(HF), which would also react with diamond. The reaction is:

\({{\rm{H}}_4}{\rm{Si}}{{\rm{O}}_4} + 4HF \to SiF + 4{H_2}O.\)

(b) Another way would be by heating the object with \({\rm{CaO}}\). The reaction is:

\({\rm{CaO}}(s) + {\rm{Si}}{{\rm{O}}_2}(s) \to {\rm{CaSi}}{{\rm{O}}_3}(l).\)

The liquid product could be removed, and only the powder \({\rm{CaO}}\) would remain, which is soluble in water. This is possible because a diamond can stand very high temperatures without melting and reacting.