Structural formula of tetraaquadichloridochromium(III) chloride

Options

A. `[(H_(2)O)_(4)Cl_(2)Cr]Cl`
B. `[Cl_(2)(H_(2)O)_(4)Cr]Cl`
C. `[Cr(H_(2)O)_(4)Cl_(2)]Cl`
D. `[Cr(H_(2)O)_(4)Cl_(3)]`

Answer

To derive the structural formula of tetraaquadichloridochromium(III) chloride, we will follow these steps:

### Step 1: Identify the components
- The name "tetraaquadichloridochromium(III) chloride" indicates the following:
- "tetra" means there are four water molecules (H2O) as ligands.
- "di" means there are two chloride ions (Cl-) as ligands.
- "chromium(III)" indicates that chromium has a +3 oxidation state.
- The term "chloride" at the end indicates that there is an additional chloride ion outside the coordination sphere.

### Step 2: Write the ligands
- The ligands are:
- 4 water molecules: \(4 \times \text{H}_2\text{O}\)
- 2 chloride ions: \(2 \times \text{Cl}^-\)

### Step 3: Write the central metal ion
- The central metal ion is chromium (Cr) in the +3 oxidation state.

### Step 4: Assemble the coordination complex
- The coordination complex can be written as:
\[ [\text{Cr}(\text{H}_2\text{O})_4(\text{Cl})_2]^{+3} \]
- Here, the chromium ion is surrounded by four water ligands and two chloride ligands.

### Step 5: Add the external chloride ion
- Since there is an additional chloride ion outside the coordination sphere, we write:
\[ \text{Cr}(\text{H}_2\text{O})_4(\text{Cl})_2 \cdot \text{Cl}^- \]

### Final Structural Formula
- The final structural formula of tetraaquadichloridochromium(III) chloride is:
\[ [\text{Cr}(\text{H}_2\text{O})_4(\text{Cl})_2]^{+3} \cdot \text{Cl}^- \]