CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
A volatile organic compound containing carbon, hydrogen, chlorine, and oxygen is studied. A 0.375 g sample of the vapor is introduced into a 125 mL flask at 95 °C. The pressure inside the flask is 755 torr.
The same 0.375 g sample is completely burned in excess oxygen, and the gaseous combustion products are collected and weighed, giving the following data:
• mass of CO₂ produced: 0.535 g
• mass of H₂O produced: 0.183 g
• mass of HCl produced: 0.148 g
Answer the questions below. (Assume ideal-gas behavior.)
(a) Calculate the molar mass of the vapor from the gas-phase data collected at 95 °C.
(b) Determine the moles of C, H, and Cl present in the original 0.375 g sample using the combustion data.
(c) Oxygen is not recovered in a separate product. Calculate the mass of oxygen in the compound by difference and determine the empirical formula of the compound.
(d) Combine your results from parts (a) and (c) to determine the molecular formula of the compound.
(e) Discuss whether the agreement between the empirical-formula molar mass and the experimentally measured molar mass supports the purity of the original sample.