Primary and secondary valencies of Cu in `[Cu(NH_(3))_(4)]SO_(4)` is

Options

A. 4,4
B. 2,4
C. 4,1
D. 4,2

Answer

To determine the primary and secondary valencies of copper (Cu) in the complex compound \([Cu(NH_3)_4]SO_4\), we will follow these steps:

### Step 1: Identify the oxidation state of Cu
The primary valency corresponds to the oxidation state of the metal ion in the complex.

1. The complex dissociates into \([Cu(NH_3)_4]^{2+}\) and \(SO_4^{2-}\).
2. Let the oxidation state of Cu be \(x\).
3. Ammonia (NH₃) is a neutral ligand, contributing 0 to the charge.
4. The overall charge of the complex ion \([Cu(NH_3)_4]^{2+}\) is +2.

Using the equation:
\[ x + 4(0) = +2 \]
This simplifies to:
\[ x = +2 \]

**Primary Valency of Cu = +2**

### Step 2: Determine the coordination number
The secondary valency refers to the coordination number, which is the number of coordinate bonds formed between the metal ion and the ligands.

1. In the complex \([Cu(NH_3)_4]^{2+}\), there are 4 ammonia (NH₃) ligands.
2. Each NH₃ ligand has one donor atom (the nitrogen atom), which forms a coordinate bond with Cu.

Thus, the coordination number (CN) can be calculated as:
\[ \text{Coordination Number} = \text{Number of Ligands} \times \text{Density} \]
Where:
- Number of ligands = 4 (from NH₃)
- Density = 1 (since each NH₃ has one donor atom)

So:
\[ \text{Coordination Number} = 4 \times 1 = 4 \]

**Secondary Valency of Cu = 4**

### Final Answer
- Primary Valency of Cu = +2
- Secondary Valency of Cu = 4