Solveeit Logo

Question

Question: A compound is made by mixing cobalt (III) nitrite and potassium nitrite solutions in the ratio of \(...

A compound is made by mixing cobalt (III) nitrite and potassium nitrite solutions in the ratio of 1:31:3. The aqueous solution of the compound showed 4 particles per molecule whereas molar conductivity reveals the presence of six electrical charges. The formula of the compound is:
A.Co(NO2)3.2KNO2Co{\left( {N{O_2}} \right)_3}.2KN{O_2}
B.Co(NO2)3.3KNO2Co{\left( {N{O_2}} \right)_3}.3KN{O_2}
C.K3[Co(NO2)6]{K_3}\left[ {Co{{\left( {N{O_2}} \right)}_6}} \right]
D.K[Co(NO2)4]K\left[ {Co{{\left( {N{O_2}} \right)}_4}} \right]

Explanation

Solution

To answer this question, you must recall addition compounds and the difference between the different types of addition compounds. Additional compounds can be either coordination compounds or double salts.

Complete step by step solution:
- Coordination compounds do not furnish all the ions which are given by the constituent compounds and they maintain their identity in an aqueous solution.
- Apart from coordination compounds, the other type of additional compound is double salts. Unlike coordination compounds, double salts are stable only in crystalline state and lose their identity in solution form.
- The salts given in options A and B are double salts while those in C and D are coordination compounds. It is given in the question that in aqueous solution, the compound formed by the addition of 1 mole of cobalt nitrite and 3 moles of potassium nitrite, furnishes 4 ions in an aqueous solution.
- In option A, we have Co(NO2)3.2KNO2Co{\left( {N{O_2}} \right)_3}.2KN{O_2}. This is a double salt and furnishes all ions in water. It forms one Co3+C{o^{3 + }}ion, 5 NO2NO_2^ - ions and 2 K+{K^ + } ions. A total of 8 ions are furnished. Thus, we can rule out this option.
- In option B, we have Co(NO2)3.3KNO2Co{\left( {N{O_2}} \right)_3}.3KN{O_2}. This is a double salt and furnishes all ions in water. It forms one Co3+C{o^{3 + }}ion, 6 NO2NO_2^ - ions and 3 K+{K^ + } ions. A total of 10 ions are furnished. Thus, we can rule out this option.
- In option C, we have K3[Co(NO2)6]{K_3}\left[ {Co{{\left( {N{O_2}} \right)}_6}} \right]. This is a coordination compound and in aqueous solution forms the three K+{K^ + } ions and one [Co(NO2)6]3{\left[ {Co{{\left( {N{O_2}} \right)}_6}} \right]^{3 - }} complex ion. A total of 4 ions are furnished which have a total of six electrical charges.

Thus, the correct option is C.

Note: Coordination compounds are the compounds in which a central metal atom is linked by coordination bond to a number of ligands, which may either be ions or neutral molecules, i.e. by donation of lone pairs by the ligands to the central metal atom. If this compound carries a positive or negative charge, it is called a complex ion. These complex ions are relatively stable and they do not lose their identity in aqueous solution like double salts.