The empirical formula represents the simplest whole-number ratio of atoms in a compound. Here's how to find it:

1. Identify the greatest common factor (GCD) of the subscripts: The GCD of 2 and 6 is 2.

2. Divide each subscript by the GCD:

* C₂ / 2 = C₁

* Cl₆ / 2 = Cl₃

3. Write the empirical formula: The empirical formula for C₂Cl₆ is CCl₃.