Explain the following
(a) Generally sulphide ores are converted into oxides before reduction.
(b) Silica is added to the sulphide ore of copper in the reverberatory furnance.

Explanation

(a)As show in Ellingha diagram which related Gibbs Free energy and temperature at below 710K.
`DeltaG_((C,CO_(2)) lt DeltaG_((C,CO_(2))` So, `CO_(2)` is a better reducing agent than CO while above 710 K it becomes a very good reducing agent.
(b) Generally, sulphide ores are converted to oxides before reduction as reduction of oxides can easily be done using C or CO depending upon metal ore and temperature.
( c) Silica is a flux added to the sulphide ore of copper in the reverberatory furnance leading to the formation of slag
`FeO+SiO_(2) to underset("Slag")(FeSiO_(3))`
(d) Carbon and hydrogen are not used as reducing agents at high temperature. At high temperature carbonl and hydrogen readily form their carbides and hydrides respectively.
(e) Vapour phase refining method is used for the purifiacation of Ti as
`Ti+2I_(2) overset(532K) to TiI_(4) overset(1700K) to 2 I_(2)`