General Princip...

Lead obtained from galena ore (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, Sn, As) as impurities it is due to the presence of these impurities that lead becomes hard and brittle.

Lead obtained from galena ore (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, Sn, As) as impurities it is due to the presence of these impurities that lead becomes hard and brittle.

All minerals are not the ore but all ores are minerals. The extraction of a particular metal depends upon several factors and overall it has to be convenient and economical.

These equilibria can be discussed in terms of thermodynamic functions.
For the reaction :
(i) $$\displaystyle M_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow MO_(s)$$
(ii) $$\displaystyle \frac{1}{2} C_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow \frac{1}{2} CO_{2(g)}$$
(iii) $$\displaystyle C_{(s)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{(g)}$$
(iii) $$\displaystyle CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$$
The temperature dependence of $$\Delta \mathring{G}$$ of reaction $$(i)$$ to $$(iv)$$ is shown in the given diagram. This is known as Ellingham diagram. With the help of Ellingham diagram, one can easily predict the most suitable reducing agent for the reduction of metal oxides.