What is the chemical formula of Aluminium sulphate?

The chemical formula of aluminum sulfate is \( \text{Al}_2(\text{SO}_4)_3 \).

Here’s a breakdown of how to determine this formula:

1. **Identify the ions involved**:
- Aluminum (Al) forms a cation with a +3 charge: \( \text{Al}^{3+} \).
- Sulfate (SO₄) forms an anion with a -2 charge: \( \text{SO}_4^{2-} \).

2. **Determine the ratio of ions to balance the charges**:
- To balance the total positive and negative charges, we need 2 aluminum ions (each with a +3 charge, totaling +6) and 3 sulfate ions (each with a -2 charge, totaling -6).

3. **Combine the ions**:
- Thus, the formula becomes \( \text{Al}_2(\text{SO}_4)_3 \), where there are 2 aluminum ions and 3 sulfate ions.

So, the formula for aluminum sulfate is \( \text{Al}_2(\text{SO}_4)_3 \).