The empirical formula for this compound can be determined by calculating the molar mass of the gold and the chlorine, and then dividing the molar mass of the gold by the molar mass of the chlorine. The molar mass of gold is 196.97 g/mol, and the molar mass of chlorine is 35.45 g/mol.
When we divide the molar mass of the gold by the molar mass of the chlorine, we get 5.56. This means that the empirical formula for this compound is AuCl5.