Question

A metal which exists as a liquid at room temperature is obtained by heating its sulphide ore in the presence of air.
(a) Name the metal and write its chemical symbol.
(b) Write the name and formula of the sulphide ore.
(c) Give the equations of chemical reactions involved in the production of metal from its sulphide ore.
(d) Name a common device in which this metal is used.
(e) Can this metal displace copper from copper sulphate solution? Why?

Answer 1

(a) The metal is mercury and its chemical symbol is Hg.

(b) Sulphide ore of mercury is cinnabar and its chemical formula is HgS (Mercury (II) sulphide).

(c) Mercury is a less reactive metal. Its ore cinnabar, HgS, is a sulphide ore. On heating the sulphide ore, mercury can be extracted. It is a sulphide ore; therefore, it is first heated with air (roasting process). This converts mercury (II) sulphide to mercury (II) oxide.

$\mathrm{2HgS}+{3O}_2\stackrel{}{\to }2\mathrm{HgO}+{2SO}_2$
Mercury (II) oxide, thus formed, is heated to around 300^oC and it gets reduced to mercury.
$\mathrm{2HgO}\stackrel{}{\to }2\mathrm{Hg}+O_2$
(d) A common device wherein mercury is used is thermometer.

(e) No, mercury cannot displace copper from its salt solution. Mercury is less reactive than copper and is placed below it in the reactivity series.