Chapter 24, Problem 55IAE

The compound ${\text{CoCl}}_{\text{2}}-{\text{2H}}_{\text{2}}\text{O}\cdot {\text{4 NH}}_{\text{2}}$ may be one of the hydrate isomers ${\text{[CoCl(H}}_{\text{2}}{\text{O)(NH}}_{\text{2}}{\text{)}}_{\text{4}}{\text{]Cl×H}}_{\text{2}}\text{O}$ or ${\text{[Co(H}}_{\text{2}}{\text{O)}}_{\text{2}}{{\text{(NH}}_{\text{2}}\text{)}}_{\text{4}}\text{]Cl}$ . A 0.10 M aqueous solution of the compound is found to have a freezing point of -0.56 °C. Determine the correct formula of the compound. The freezing-point depression constant for water is 1.86 mol kg-1 °C, and for aqueous solutions, molarity and molality can be taken as approximately equal.