Question

Which of the following is Rinmann’s green?
A) ${\text{ZnO}}$
B) ${\text{ZnS}} + {\text{BaS}}{{\text{O}}_{\text{4}}}$
C) ${\text{ZnS}}{{\text{O}}_{\text{4}}} \cdot {\text{7}}{{\text{H}}_{\text{2}}}{\text{O}}$
D) ${\text{ZnO}} \cdot {\text{CoO}}$

Answer 1

To solve this we must know that Rinmann’s green is also known as zinc green or cinnabar green or turquoise green. Rinmann’s green was discovered by a Swedish chemist Sven Rinmann. And thus, Rinmann’s green is named after its discoverer.

Complete step-by-step answer:
${\text{ZnO}}$ is zinc oxide. Zinc oxide is also known as calamine or Chinese white. Thus, option (A) is not correct.
${\text{ZnS}} + {\text{BaS}}{{\text{O}}_{\text{4}}}$ is barium zinc sulphate sulphide. Barium zinc sulphate sulphide is also known as lithopone. Thus, option (B) is not correct.
${\text{ZnS}}{{\text{O}}_{\text{4}}} \cdot {\text{7}}{{\text{H}}_{\text{2}}}{\text{O}}$ is zinc sulphate heptahydrate. Zinc sulphate heptahydrate is also known as white vitriol or goslarite. Thus, option (C) is not correct.
${\text{ZnO}} \cdot {\text{CoO}}$ is known as Rinmann’s green. Rinmann’s green is also known as zinc green or cinnabar green or turquoise green or cobalt green.
Rinmann’s green is obtained by doping cobalt oxide into zinc oxide. The structure of Rinmann’s green is similar to that of spinels.
Rinmann’s green is insoluble in water. Rinmann’s green is generally used as a chromophore. But as Rinmann’s green is very expensive it is not very widely used. Instead chromium(II) oxide is used as a chromophore. Thus, Rinmann’s green is ${\text{ZnO}} \cdot {\text{CoO}}$.

Thus, the correct option is (D) ${\text{ZnO}} \cdot {\text{CoO}}$.

Note: The structure and colour of composition of Rinmann’s green depends on the number of zinc and cobalt atoms in the crystal lattice of Rinmann’s green. Rinmann’s green sometimes resembles wurtzite and appears as an intense green in colour. Sometimes resembles sodium chloride structure and appears pink in colour.