Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?
What is the significance of leaching in the extraction of aluminium?
The reaction,
Cr2O3 + 2 Al → Al2 O3 + 2 Cr (ΔG0 = – 421 kJ)
is thermodynamically 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?
Copper can be extracted by hydrometallurgy but not zinc. Explain.
What is the role of depressant in froth floatation process?
Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?
Explain:
Zone refining
Column chromatography.
Out of C and CO, which is a better reducing agent at 673 K?
Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present?
Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.
Write chemical reactions taking place in the extraction of zinc from zinc blende.
State the role of silica in the metallurgy of copper.
What is meant by the term “chromatography”?
What criterion is followed for the selection of the stationary phase chromatography?
Describe a method for refining nickel.
How can you separate alumina from silica in a bauxite ore associated with silica? Give equations, if any.
Giving examples, differentiate between ‘roasting’ and ‘calcination’.
How is ‘cast iron’ different from ‘pig iron”?
Differentiate between “minerals” and “ores”.
Why is copper matte put in the silica lined converter?
What is the role of cryolite in the metallurgy of aluminium?
How is leaching carried out in case of low-grade copper ores?
Why is zinc not extracted from zinc oxide through reduction using CO?
The value of for the formation of Cr2 O3 is – 540 kJmol−1and that of Al2 O3 is – 827 kJmol−1. Is the reduction of Cr2 O3 possible with Al?
Out of C and CO, which is a better reducing agent for ZnO?
The choice of a reducing agent in a particular case depends on the thermodynamic factor. How far do you agree with this statement? Support your opinion with two examples.
Name the processes from which chlorine is obtained as a by-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?
What is the role of graphite rod in the electrometallurgy of aluminium?
Outline the principles of refining of metals by the following methods:
(i) Zone refining
(ii) Electrolytic refining
(iii) Vapour phase refining
Predict conditions under which Al might be expected to reduce MgO. (Hint: See Intext question 6.4)
