Molecular Weight of Volatile Liquid Using Dumas Method
OBJECTIVE: * To determine the molecular weight of a volatile liquid by using Dumas method.
METHOD:
MATERIAL | CHEMICALS | 125 mL Erlenmeyer flask | Known liquid (2-propanol) | Rubber band | Unknown liquid | Boiling chips | | Watch glass | | 100 mL graduated cylinder | | Pin | | 600 mL beaker | | Hot plate | | Thermometer | | Room temperature water | | 6 × 6 and 8 × 8 aluminium foil | |
PROCEDURE:
SAFETY * Lab Coat and Safety Goggles. * Keep the bottles tightly close when not in use. * Do not drink or eat in laboratory.
OBSERVATION:
Weight balance detail: Instrument Number | 5 | Model Number | MS204-S/03 | Manufacturer | METTLE TOLEDO | Type | New Classic MF |
Boiling chips detail:- VWR scientific, Inc. Porous boiling chips VWR cat. # 26397 - 409
Given sample: - 2-propanol (CH3CHOHCH3)
Molecular weight: - 60.08 gm/mole
Sample volume taken: - 2 mL | Flask 1 | Flask 2 | Flask 3 | Mass of flask and condensed vapour | 77.8735 gm | 77.8768 gm | 77.8750 gm | Mass of empty flask apparatus | 77.6050 gm | 77.6059 gm | 77.6055 gm | Mass of condensed vapour | 0.2685 gm | 0.2709 gm | 0.2695 gm |
| Flask 1 | Flask 2 | Flask 3 | Temperature of water | 90˚C (363 K) | 93˚C (366 K) | 95˚C (368 K) | Barometric pressure (Assume) | 1 atm | 1 atm | 1 atm |
| Flask 1 | Flask 2 | Flask 3 | Volume of flask | 147 mL | 143 mL | 143 mL |
Temperature: - 93˚C (366 K)
Pressure: - 1 atm => 760 mmHg
PV=nRT n = W/M where, R = 0.0821 atm.L/mol.K
Flask 1: - M = WRT = 0.2685 × 0.0821 × 363 PV 1 × 0.143 * 55.9574 gm/mole
Flask 2: - M = WRT = 0.2709 × 0.0821 × 366 PV 1 × 0.143 * 56.3889 gm/mole
Flask 3: - M = WRT = 0.2695 × 0.0821 × 368 PV 1 × 0.143 * 56.9395 gm/mole
Average = 55.9574 + 56.3889 + 56.9395 3 * 56.4286 gm/mole
% error = Accepted value – experiment value × 100
METHOD:
MATERIAL | CHEMICALS | 125 mL Erlenmeyer flask | Known liquid (2-propanol) | Rubber band | Unknown liquid | Boiling chips | | Watch glass | | 100 mL graduated cylinder | | Pin | | 600 mL beaker | | Hot plate | | Thermometer | | Room temperature water | | 6 × 6 and 8 × 8 aluminium foil | |
PROCEDURE:
SAFETY * Lab Coat and Safety Goggles. * Keep the bottles tightly close when not in use. * Do not drink or eat in laboratory.
OBSERVATION:
Weight balance detail: Instrument Number | 5 | Model Number | MS204-S/03 | Manufacturer | METTLE TOLEDO | Type | New Classic MF |
Boiling chips detail:- VWR scientific, Inc. Porous boiling chips VWR cat. # 26397 - 409
Given sample: - 2-propanol (CH3CHOHCH3)
Molecular weight: - 60.08 gm/mole
Sample volume taken: - 2 mL | Flask 1 | Flask 2 | Flask 3 | Mass of flask and condensed vapour | 77.8735 gm | 77.8768 gm | 77.8750 gm | Mass of empty flask apparatus | 77.6050 gm | 77.6059 gm | 77.6055 gm | Mass of condensed vapour | 0.2685 gm | 0.2709 gm | 0.2695 gm |
| Flask 1 | Flask 2 | Flask 3 | Temperature of water | 90˚C (363 K) | 93˚C (366 K) | 95˚C (368 K) | Barometric pressure (Assume) | 1 atm | 1 atm | 1 atm |
| Flask 1 | Flask 2 | Flask 3 | Volume of flask | 147 mL | 143 mL | 143 mL |
Temperature: - 93˚C (366 K)
Pressure: - 1 atm => 760 mmHg
PV=nRT n = W/M where, R = 0.0821 atm.L/mol.K
Flask 1: - M = WRT = 0.2685 × 0.0821 × 363 PV 1 × 0.143 * 55.9574 gm/mole
Flask 2: - M = WRT = 0.2709 × 0.0821 × 366 PV 1 × 0.143 * 56.3889 gm/mole
Flask 3: - M = WRT = 0.2695 × 0.0821 × 368 PV 1 × 0.143 * 56.9395 gm/mole
Average = 55.9574 + 56.3889 + 56.9395 3 * 56.4286 gm/mole
% error = Accepted value – experiment value × 100