Question

The molecular formula of a coordinate complex is CoH\(_{12}\)O\(_6\)Cl\(_3\). When one mole of this aqueous solution of complex is reacted with excess of aqueous AgNO\(_3\) solution, three moles of AgCl were formed. What is the correct formula of the complex?

• A. [Co(H\(_2\)O)\(_6\)]Cl\(_3\)
• B. [Co(H\(_2\)O)\(_6\)]Cl\(_2\)H\(_2\)O
• C. [Co(H\(_2\)O)\(_6\)]Cl\(_3\)(H\(_2\)O)
• D. [Co(H\(_2\)O)\(_6\)]Cl\(_3\)(H\(_2\)O)

Hint:

When determining the formula of a complex, consider the stoichiometry of the reaction with other compounds (like AgNO\(_3\)) to identify the number of ligands and counterions.

Answer 1

The Correct Option is A

When one mole of the given complex reacts with excess AgNO\(_3\) solution, three moles of AgCl are formed. This suggests that the complex contains three chloride ions. The correct formula of the complex is [Co(H\(_2\)O)\(_6\)]Cl\(_3\), where Co is coordinated to six water molecules, with three chloride ions as counterions.