1.76 g of the volatile liquid was able to fill a 288 mL Erlenmeyer flask at 99.8 kPa and 80°C.

Question

what's the empirical formula for this gas?

Answer 1

Use the ideal gas law PV = nRT and solve for n (moles of gas)

n = PV/RT = (99.8 kPa)(0.288 L)/(8.314 L-kPa/K-mol)(353K)

n = 0.00976 moles of gas

Since this represents 1.76 g, the molar mass of the gas = 1.76 g/0.00976 moles = 180.3 g/mole

From your previous question, the empirical formula is C2H4O. Without the additional information provided in your previous question, we can't know the empirical formula.