The choice of a reducing agent in a particular case depends on thermodynamic factor. How far do you agree with this statement? Support your opinion with two examples.
Carbon monoxide is more effective agent that carbon below 983 K but above this temperature the reverse is true. How would you explain this?
In the production of iron from its oxide ore, the mixture of ore, coke and limestone is heated with a blast of air in furnace. Below 983K oxides of iron are reduced by carbon monoxide to iron.
Fe2O3 +CO → 2FeO +CO2
FeO +CO → Fe + CO2
Above 983K, Fe2O3 undergoes reduction by hot coke to iron. This region is called fusion zone
Fe2O3 +3C → 2Fe +3CO +Heat
Thus carbon monoxide is more effective agent than carbon below 983K.
The value of ΔrG° for formation of Cr2O3 is – 540 kJmol–1 and that of Al2O3 is – 827 kJ mol-1. Is the reduction of Cr2O3 possible with Al?
Predict the modes of occurrence of the following three types of metals:
(i) Highly reactive (e.g., Na)
(ii) Moderately reactive (e.g., Fe)
(iii) Noble metal (e.g., Au)
How do non-metals occur in nature? How are they extracted/isolated from their natural resources?
Name the chief ores of tin, iron and aluminium. What methods are employed for the concentration/purification of their ores?
Name three ores which are concentrated by froth-floatation process. What is meant by depressant?
Discuss some of the factors which need consideration before deciding on the method of extraction of metal from its ore.
You are provided with samples of some impure metals such as zinc, copper and germanium. Which methods could you recommend for the purification of each of these metals?