Which one is the correct formula of aluminium sulphate?

Options

A. `AlSO_(4)`
B. `Al_(2)(SO_(4))_(3)`
C. `Al_(3)(SO_(4))_(2)`
D. `Al(SO_(4))_(3)`

Answer

To determine the correct formula for aluminum sulfate, we need to follow these steps:

### Step-by-Step Solution:

1. **Identify the Ions Present**:
- Aluminum sulfate consists of aluminum ions (Al³⁺) and sulfate ions (SO₄²⁻).

2. **Determine the Charges of the Ions**:
- The charge on the aluminum ion (Al) is +3 (Al³⁺).
- The charge on the sulfate ion (SO₄) is -2 (SO₄²⁻).

3. **Balance the Charges**:
- To balance the total positive and negative charges, we can use the method of cross-multiplication.
- The aluminum ion has a charge of +3, and we need to find out how many sulfate ions are required to balance this charge.
- The sulfate ion has a charge of -2.

4. **Calculate the Number of Each Ion Needed**:
- Let’s say we need 'x' sulfate ions to balance the charge from aluminum.
- The total positive charge from aluminum will be: \( 3 \times 2 = +6 \) (since we will need 2 aluminum ions).
- The total negative charge from sulfate will be: \( -2 \times 3 = -6 \) (since we will need 3 sulfate ions).
- This gives us a balanced equation: \( +6 + (-6) = 0 \).

5. **Write the Formula**:
- From the calculations, we find that we need 2 aluminum ions and 3 sulfate ions.
- Therefore, the formula for aluminum sulfate is \( \text{Al}_2(\text{SO}_4)_3 \).

### Final Answer:
The correct formula for aluminum sulfate is **Al₂(SO₄)₃**.

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