Question

What is the color of the precipitate in this reaction:
${\text{CoC}}{{\text{l}}_{\text{2}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{ }} \to {\text{ ?}}$
(A) Pink
(B) Black
(C) Blue
(D) Red

Answer 1

Hint: First we will predict the product by calculating the oxidation states of elements and seems like it is a double dissociation reaction, so the product formed will be exchange of the ions with each other. Then we will see the solubility of the product to predict the precipitate among the products.

Complete step by step answer:
As we can see it is a double displacement reaction in which the cations and anions present in the reaction exchanges within themselves to form a product. First, we will see the ions in reaction. ${\text{CoC}}{{\text{l}}_{\text{2}}}$ has one cation and two anions ${\text{C}}{{\text{o}}^{{\text{2 + }}}}{\text{ and 2C}}{{\text{l}}^{\text{ - }}}$ respectively and ${\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ has two cation and one anion ${\text{2N}}{{\text{a}}^{\text{ + }}}{\text{ and CO}}_{\text{3}}^{{\text{2 - }}}$ respectively. Now since the reaction is a double displacement reaction the ions exchange themselves. So, the whole balanced reaction will be:
${\text{CoC}}{{\text{l}}_{\text{2}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{ }} \to {\text{ CoC}}{{\text{O}}_{\text{3}}}{\text{ + 2NaCl}}$
This cobalt carbonate formed here is an inorganic compound which is found in the cobalt ores. It is one of the intermediates formed during hydrometallurgical purification of cobalt ore. It is a red colored salt. It is paramagnetic in nature. On prolonged cooling in the solution the precipitate in this reaction turns into pink color.

So, the correct answer is Option A .

Note: Cobalt carbonate is mainly used to produce cobalt carbonyls as they are important substrates for many reactions. Since cobalt is among the essential elements in nutrition of the diet so it is taken as dietary supplements too.

The main ore from which the cobalt carbonate is obtained is called sphericality. It is a rare ore to be found and found mostly in the Congo state of Africa. Cobalt calcite is also a variety of ore for cobalt which is quite similar to spherocobaltite.