The aqueous solution containing one mole of `CoCl_(3).5NH_3` consumed 2 mol of silver nitrate solution for precipitation of free chloride ions. The formula of the compound should be

Options

A. `[Co(NH_3)_5Cl]Cl_2`
B. `[Co(NH_3)_6Cl]Cl_2`
C. `[Co(NH_3)_5Cl_2]Cl`
D. `[Co(NH_3)_5Cl_3]`

Answer

To solve the problem, we need to determine the correct formula for the coordination compound `CoCl3.5NH3` based on the information given about its reaction with silver nitrate.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The compound `CoCl3.5NH3` reacts with silver nitrate (AgNO3) to precipitate silver chloride (AgCl).
- It is mentioned that 2 moles of AgNO3 are consumed, which means that 2 moles of AgCl are formed.

2. **Identifying the Chloride Ions**:
- Since 2 moles of AgCl are formed, this indicates that there are 2 free chloride ions (Cl⁻) in the solution.
- The coordination compound must therefore contain 2 chloride ions that are not coordinated to the cobalt ion.

3. **Determining the Coordination Number**:
- The coordination number of cobalt in this case is likely 6, which is typical for octahedral complexes.
- The formula `CoCl3.5NH3` suggests that there are 5 ammonia (NH3) ligands coordinated to the cobalt ion.

4. **Constructing the Formula**:
- The cobalt ion (Co) is in the center, surrounded by 5 NH3 ligands and 2 Cl⁻ ions.
- The overall charge of the compound must be neutral. Cobalt in this case is likely in the +3 oxidation state (Co³⁺), which balances the 2 negative charges from the chloride ions and the neutral ammonia ligands.

5. **Final Formula**:
- The final formula of the coordination compound can be written as [Co(NH3)5Cl2]Cl, where:
- Co is the central metal ion.
- NH3 are the neutral ligands.
- Cl2 are the two chloride ions coordinated to the metal.
- The additional Cl⁻ outside the coordination sphere balances the charge.

### Conclusion:
The formula of the compound is [Co(NH3)5Cl2]Cl.