The oxidation number of platinum in `[Pt(NH_3)_5 Cl]Cl_3` is-

Options

A. 2
B. 3
C. 4
D. 6

Answer

To find the oxidation number of platinum in the coordination compound \([Pt(NH_3)_5Cl]Cl_3\), we can follow these steps:

### Step 1: Identify the ligands and their charges
In the complex \([Pt(NH_3)_5Cl]^{3+}\):
- There are 5 ammonia (\(NH_3\)) ligands, which are neutral (charge = 0).
- There is 1 chloride (\(Cl\)) ligand, which has a charge of -1.

### Step 2: Write the equation for the oxidation number
Let the oxidation number of platinum be \(X\). The overall charge of the complex ion \([Pt(NH_3)_5Cl]\) must equal the total charge contributed by the ligands and the platinum. The equation can be set up as follows:

\[ X + (5 \times 0) + (-1) = \text{Charge of the complex ion} \]

### Step 3: Determine the charge of the complex ion
The entire compound \([Pt(NH_3)_5Cl]Cl_3\) is neutral. The three chloride ions outside the complex contribute a charge of \(-3\) (since each \(Cl\) has a charge of -1). Therefore, the charge of the complex ion \([Pt(NH_3)_5Cl]\) must be \(+3\) to balance the -3 from the three chloride ions.

### Step 4: Set up the equation
Now we can substitute the charge of the complex ion into our equation:

\[ X - 1 = +3 \]

### Step 5: Solve for \(X\)
Rearranging the equation gives:

\[ X = +3 + 1 \]
\[ X = +4 \]

### Conclusion
The oxidation number of platinum in the complex \([Pt(NH_3)_5Cl]Cl_3\) is \(+4\).