Final answer:
To find the molecular formula, calculate the molar mass using the Ideal Gas Law, then divide by the empirical formula mass to get the integer multiple n. Finally, multiply the empirical formula by n.
Step-by-step explanation:
The question asks for the determination of a molecular formula based on the characteristics of a gaseous compound in a flask at given conditions. To find the molecular formula, we first need to use the Ideal Gas Law (PV = nRT) to find the amount of moles of the compound. The conditions provided are: a volume (V) of 256 mL or 0.256 L, temperature (T) is 373 K, and pressure (P) is 750 torr which we convert to atmospheres by dividing by 760 torr/atm, yielding approximately 0.987 atm. Thus, the number of moles (n) can be determined using R, the universal gas constant 0.0821 L atm mol⁻¹K⁻¹.
Once we have the number of moles, we calculate molar mass by dividing the mass of the sample (0.800 g) by the moles of gas. With the empirical formula CHCl, we establish the empirical formula mass (EFM) by summing the atomic masses of carbon (C), hydrogen (H), and chlorine (Cl). Finally, we find the integer multiple (n), which connects the empirical and molecular formulas, by dividing the molar mass by the EFM. The molecular formula of the compound is the empirical formula multiplied by n.
Here's the calculation:
- Using the Ideal Gas Law:
PV = nRT → n = PV/RT - n = (0.987 atm * 0.256 L) / (0.0821 L atm mol⁻¹K⁻¹ * 373 K)
- Calculate molar mass (MM) of the compound:
MM = mass of gas / moles of gas - Determine the empirical formula mass (EFM) based on CHCl,
EFM = mass of C + mass of H + mass of Cl - Find integer multiple (n): MM / EFM
- The molecular formula is CHCl * n
To provide a complete answer, details on the empirical formula mass (EFM) and the actual calculations would be given, but these details go beyond the response format.