An isomer of the hydrate CrCl ₃ 6 H ₂ O is dissolved in water. When one mole of this complex is treated with an excess of silver nitrate solution, two moles of a white precipitate are formed. Identify the correct structural formula of this isomer and the type of structural isomerism it illustrates when compared to the other hydrate forms.

Step-by-step solution

The reaction of the complex with excess AgNO ₃ yields two moles of AgCl precipitate per mole of the complex. This indicates that there are exactly two ionizable chloride ions present outside the coordination sphere. Given the empirical formula CrCl ₃ 6 H ₂ O , placing two Cl ^- ions outside leaves one Cl ^- ion and five H ₂ O molecules inside the coordination sphere to satisfy the secondary valency (coordination number) of 6 for chromium. The structural formula is therefore [ Cr ( H ₂ O )₅ Cl ] Cl ₂ H ₂ O . Isomers