Which of the ores mentioned in Table 6.1. could be concentrated by magnetic separation method?
Table 6.1 Principal ores of some important metal.
The reaction.
Cr2O3 + 2Al → Al2O3 + 2Cr (ΔG° = – 421 kJ)
is thermodyanmically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?
Is it true that under certain conditions. Mg can reduce Al2O3 and Al can reduce MgO? What are those conditions?
The role of depressant in froth floatation process is to prevent certain type of materials from forming the froth with bubbles. For example, to separate two sulphide ores (ZnS and Pbs), NaCN is used as a depressant which selectively allows PbS to come with froth, but prevents ZnS from coming to froth. This happens because NaCN reacts with ZnS to form Na2[Zn(CN)4].
4NaCN+ZnS → Na2[Zn(CN)4] + Na2S
Titanium is a metal of modern times. It is obtained as oxide. Why it could not be extracted earlier despite its wide occurence?
Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present?
What criterion is followed for the selection of the stationary phase in chromatography?