1. Find the Mass of Oxygen

* Mass of crucible + calcium oxide = 38.850 g

* Mass of crucible = 38.500 g

* Mass of calcium oxide = 38.850 g - 38.500 g = 0.350 g

* Mass of oxygen = Mass of calcium oxide - Mass of calcium = 0.350 g - 2.50 g = -2.15 g

2. Convert Masses to Moles

* Moles of calcium (Ca) = 2.50 g / 40.08 g/mol = 0.0624 mol

* Moles of oxygen (O) = -2.15 g / 16.00 g/mol = -0.134 mol

3. Find the Simplest Mole Ratio

* Divide both mole values by the smaller value:

* Ca: 0.0624 mol / 0.0624 mol = 1

* O: -0.134 mol / 0.0624 mol = -2.15

4. Round to the Nearest Whole Number Ratio

* Since we're dealing with a simple ionic compound, the mole ratio should be close to whole numbers. In this case, the ratio of Ca:O is approximately 1:2.

5. Write the Empirical Formula

* The empirical formula for the calcium oxide is CaO₂.

Important Note: The negative value for oxygen moles is an error in the calculation. The mass of oxygen cannot be negative. There seems to be an issue with the given information. The mass of the crucible + oxide should be greater than the mass of the crucible alone.

To get a more accurate answer, please double-check the given masses and make sure they are correct.