The empirical formula for this compound that contain 31.14%sulfur and 68.86%chlorine by mass

The empirical formula is SCl_2.

The empirical formula (EF) is the simplest whole-number ratio of atoms in a compound.

The ratio of atoms is the same as the ratio of moles.

So, our job is to calculate the molar ratio of S to Cl.

Assume that you have 100 g of sample.

Then it contains 31.14 g S and 68.86 g Cl.

Step 1. Calculate the moles of each element

Moles of S = 31.14 g S × (1 mol S/(32.06 g S) = 0.971 30 mol S  

Moles of Cl = 68.86 g Cl × (1 mol Cl/35.45 g Cl) = 1.9425 mol Cl

Step 2. Calculate the molar ratio of each element

Divide each number by the smallest number of moles and round off to an integer

S:Cl = 0.971 30: 1.9425 = 1:1.9998 ≈ 1:2

Step 3: Write the empirical formula

EF = SCl_2