A compound of Ca, C, N, and S was subjected to quantitative analysis and formula mass determination, and the following data were recorded. A 0.250-g sample was mixed with Na2CO3 to convert all of the Ca to 0.160-g of CaCO3. A 0.115-gm sample was carried through a series of reactions until all of its S was changed to 0.334-g of BaSO4. A 0.712-gm sample was processed to liberate all of its N as NH3, and 0.155-g NH3 was obtained. The formula mass was found to be 156-g/mol. Determine the empirical formula of this compound.