How are the less reactive metals (which are quite low in the reactivity series) extracted? Explain with the help of an example.
The ores of less reactive metals like copper and mercury are placed at the bottom of the reactivity series. Metals are extracted from these ores by heating them alone. We should note that ores of copper can be extracted by reduction with carbon (copper (I) oxide) as well as heating alone (copper (I) sulphide).
Let us explain this by taking the example of extraction of mercury from its cinnabar ore (HgS). Cinnabar is a sulphide ore. On heating the ore, mercury can be extracted. It is a sulphide ore; therefore, it is first heated in the presence of surplus air (roasting). This converts mercury (II) sulphide to mercury (II) oxide.
Mercury (II) oxide is then heated to around 300°C On heating, it gets reduced (decomposes) to mercury metal and oxygen gas is released.