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 for tetraaquadichloridochromium(III) chloride, we will follow these steps:

### Step 1: Identify the central metal atom
The central metal atom in this coordination compound is chromium (Cr).

### Step 2: Determine the oxidation state of chromium
The name "chromium(III)" indicates that chromium has an oxidation state of +3.

### Step 3: Identify the ligands
The ligands in this compound are:
- Tetraqua (4 water molecules, H₂O)
- Dichlorido (2 chloride ions, Cl⁻)

### Step 4: Write the ligands in square brackets
The ligands will be enclosed in square brackets. Since there are 4 water molecules, we denote this as [H₂O]₄, and for the 2 chloride ions, we denote this as [Cl]₂. Therefore, we can write the ligands as:

\[ [Cr(H₂O)₄(Cl)₂] \]

### Step 5: Determine the overall charge
- The charge of chromium is +3.
- Each water molecule (H₂O) is neutral (0 charge), and there are 4 of them, contributing 0 to the overall charge.
- Each chloride ion (Cl⁻) has a charge of -1, and with 2 chloride ions, they contribute -2 to the overall charge.

Calculating the total charge:
\[ +3 (from \, Cr) + 0 (from \, H₂O) - 2 (from \, Cl) = +1 \]

### Step 6: Write the counter ion
Since the overall charge of the complex ion is +1, we need one chloride ion (Cl⁻) as a counter ion to balance the charge.

### Step 7: Combine the complex ion and the counter ion
The final structural formula of the compound will be written as:

\[ [Cr(H₂O)₄(Cl)₂]Cl \]

### Final Answer:
The structural formula of tetraaquadichloridochromium(III) chloride is:

\[ [Cr(H₂O)₄(Cl)₂]Cl \]

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