The formula of ammonium sulfate is (NH₄)₂SO₄ - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2016 - Paper 1

To find the empirical formula, we need to determine the simplest ratio of the elements. In (NH₄)₂SO₄, we have:

• 2 nitrogen (N)
• 8 hydrogen (H) (since there are 4 H per ammonium group and 2 groups)
• 1 sulfur (S)
• 4 oxygen (O).

Now, we express the formula in terms of the lowest whole number ratio of the elements:

• N: 2
• H: 8
• S: 1
• O: 4

All these numbers can be divided by 2, giving the empirical formula: N₁H₄S₁O₂ or simply NH₂SO₂.