The purest form of iron is prepared by oxidising impurities from cast iron in a reverberatory furnace. Which iron ore is used to line the furnace? Explain by giving reaction.
(a) Haematite $\left(\mathrm{Fe}_2 \mathrm{O}_3\right)$ ore is used to line the furnace.
(b) $\underset{\substack{\text { Haemattie } \\ \text { lining }}}{\mathrm{Fe}_2 \mathrm{O}_3}+\underset{\begin{array}{c}\text { Impurtilies } \\ \text { (present in cast iron) }\end{array}}{3 \mathrm{C}} \longrightarrow \underset{\begin{array}{c}\text { Wrought } \\ \text { iron }\end{array}}{2 \mathrm{Fe}}+3 \mathrm{CO}$
The mixture of compounds A and B is passed through a column of $\mathrm{Al}_2 \mathrm{O}_3$ by using alcohol as eluant. Compound A is eluted in preference to compound B . Which of the compounds A or B, is more readily adsorbed on the column?
Compounds which are adsorbed to the more extent comes out later while the another one which absorbed to the less extent comes out readily. Since, compound ' $A$ ' comes out before compound ' $B$ ', the compound ' $B$ ' is more readily adsorbed on the column.
Why is sulphide ore of copper heated in a furnace after mixing with silica?
Silica (flux) being an acidic flux removes the impurities of iron oxide the basic impurity, by reacting with it. Thus, iron silicate (slag) is formed.
$$\underset{\text { Gangue }}{\mathrm{FeO}}+\underset{\text { Flux }}{\mathrm{SiO}_2} \longrightarrow \underset{\text { Slag }}{\mathrm{FeSiO}_3}$$
Why are sulphide ores converted to oxide before reduction?
This is because oxides are reduced to metals easily while sulphides are not. So, sulphide ores are converted to oxide before reduction.
Which method is used for refining Zr and Ti ? Explain with equation.
Zr and Ti are refined by van Arkel method. It involves 2 steps
(a) Formation of iodide e.g., zirconium
$$\mathrm{Zr}+2 \mathrm{I}_2 \longrightarrow \mathrm{ZrI}_4$$
(b) Decomposition of iodide
$\mathrm{ZrI}_4 \xrightarrow{1800 \mathrm{~K}} \underset{\text { Pure }}{\mathrm{Zr}}+2 \mathrm{I}_2$