On treatment of 100 mL of 0.1 M solution of `COCl_(3).6H_(2)O` with excess of `AgNO_(3), 1.2 xx 10^(22)` ions are precipitated. The complex is

Options

A. (a) [Co(H2O)4Cl2 ]Cl.2H2O
B. (b) [Co(H2O)3Cl3 ] .3H2O
C. (c) [Co(H2O)6]Cl3
D. (d) [Co(H2O)5Cl] Cl2 .H2O

Answer

To solve the problem, we need to determine the structure of the complex `COCl3.6H2O` based on the information given about the number of ions precipitated when treated with excess `AgNO3`.

### Step-by-Step Solution:

1. **Calculate the moles of the complex**:
- Given the volume of the solution is 100 mL and the molarity is 0.1 M, we can calculate the moles of `COCl3.6H2O` using the formula:
\[ \text{Moles} = \text{Molarity} \times \text{Volume (L)} \]
- Convert 100 mL to liters:
\[ 100 \, \text{mL} = 0.1 \, \text{L} \]
- Now calculate the moles:
\[ \text{Moles of } COCl3.6H2O = 0.1 \, \text{M} \times 0.1 \, \text{L} = 0.01 \, \text{moles} \]

2. **Determine the number of ions precipitated**:
- The problem states that `1.2 \times 10^{22}` ions are precipitated when treated with excess `AgNO3`.
- To find the number of moles of ions, we use Avogadro's number:
\[ \text{Number of moles} = \frac{\text{Number of ions}}{\text{Avogadro's number}} = \frac{1.2 \times 10^{22}}{6.022 \times 10^{23}} \approx 0.0199 \, \text{moles} \approx 0.02 \, \text{moles} \]

3. **Relate the moles of chloride ions to the moles of the complex**:
- The moles of chloride ions that precipitate out correspond to the moles of the complex. Since the complex has chloride ions both inside and outside the coordination sphere, we need to determine how many are outside.
- Let \( x \) be the number of chloride ions outside the coordination sphere and \( y \) be the number of chloride ions inside the coordination sphere. The total moles of chloride ions can be expressed as:
\[ x + y = \text{moles of complex} \times \text{number of chloride ions per complex} \]
- Since we have 0.02 moles of chloride ions precipitated and 0.01 moles of the complex, we can set up the equation:
\[ x = 2 \times 0.01 = 0.02 \text{ moles of Cl}^- \]

4. **Determine the structure of the complex**:
- From the calculation, we have determined that there are 2 chloride ions outside the coordination sphere and 1 inside. Therefore, the structure of the complex can be inferred as:
\[ \text{Complex} = [Co(H2O)5Cl]Cl2 \]
- This indicates that there are 5 water molecules and 1 chloride ion coordinated to cobalt, while 2 chloride ions are present outside the coordination sphere.

### Final Answer:
The complex is `Co(H2O)5Cl` with 2 chloride ions outside the coordination sphere.

---