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

To derive the empirical formula from the compound ammonium sulfate, we begin with its molecular formula, which is (NH₄)₂SO₄.

1. Determine the number of atoms of each element:

   • Nitrogen (N): 2 from (NH₄)₂
   • Hydrogen (H): 8 from (NH₄)₂
   • Sulfur (S): 1 from SO₄
   • Oxygen (O): 4 from SO₄

2. Write the total counts:

   • N: 2
   • H: 8
   • S: 1
   • O: 4

3. Find the greatest common divisor (GCD): The common divisors of 2, 8, 1, and 4 is 1, since 1 is the only factor that can divide all counts without leaving a remainder.

4. Divide by GCD:

   • N: 2 ÷ 1 = 2
   • H: 8 ÷ 1 = 8
   • S: 1 ÷ 1 = 1
   • O: 4 ÷ 1 = 4

5. Write the empirical formula: The empirical formula is thus represented as N₂H₈SO₄.

6. Simplification: To present it in commonly used terms, the empirical formula can be simplified or represented as N₂H₈O₄. However, because S is included, the final answer would typically remain as N₂H₄SO₄ unless simplified for stoichiometric representation.