The co-ordination number of Al is potassium trioxalato aluminate (III) is

Options

A. 3
B. 6
C. 8
D. None of these

Explanation

To determine the coordination number of aluminum in potassium trioxalatoaluminate(III), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Complex**: The complex given is potassium trioxalatoaluminate(III). This indicates that aluminum (Al) is the central metal ion, and oxalate (C2O4) is the ligand.

2. **Write the Molecular Formula**: The molecular formula can be derived from the name. Since "tri" indicates three oxalate ligands, the formula can be written as:
\[ K_3[Al(C_2O_4)_3] \]
Here, K represents potassium ions outside the coordination sphere.

3. **Understand the Ligand**: The oxalate ion (C2O4) carries a charge of -2. Since there are three oxalate ligands, the overall charge contributed by the ligands is:
\[ 3 \times (-2) = -6 \]
Therefore, the aluminum ion must be in the +3 oxidation state to balance the -6 charge from the three oxalate ligands.

4. **Determine Coordination Number**: The coordination number is defined as the number of atoms (or ligands) directly bonded to the central metal ion. In this case, each oxalate ion (C2O4) acts as a bidentate ligand, meaning it can bond through two oxygen atoms.

5. **Calculate the Total Number of Bonding Sites**: Since there are three oxalate ligands and each ligand binds through two donor atoms (the two oxygen atoms), the total number of bonding sites is:
\[ 3 \text{ ligands} \times 2 \text{ donor atoms per ligand} = 6 \]

6. **Conclusion**: Therefore, the coordination number of aluminum in potassium trioxalatoaluminate(III) is 6.

### Final Answer:
The coordination number of Al in potassium trioxalatoaluminate(III) is **6**.

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