AIM: To determine the experimental heat of combustion of methanol (CH3OH) and ethanol (CH3CH2OH). To decide which would be a better choice to take on a camping trip.
MATERIALS: 1 Copper container 1 Clamp
1 Spirit Lamp with Wick Ethanol
1 Retort Stand Methanol
1 Box of Matches Water
1 Electronic Balance Thermometer
Firstly, Measure the weight of the empty Copper container on the electronic balance. Record your results in a table.
Secondly, fill the copper container with 100ml of water.
Thirdly, Attach the copper container to the clamp which is them attached to the retort stand.
Fourthly, Measure the weight of the spirit burner containing known amount of Methanol (CH3OH).
Fifthly, Measure the initial temperature of the water with the thermometer. Then light the spirit lamp's wick and place it under the copper container.
Sixthly, stir the water using the thermometer and constantly check the temperature.
Once the temperature is 10oC greater than the initial temperature, extinguish the spirit burner.
Seventhly, reweigh the mass of the spirit burner.
Eighthly, Repeat steps 1 through to 7 for ethanol (CH3CH2OH).
The combustion of Methanol and Ethanol can be represented through:
Methanol: 2CH3OH(l) + 3O2(g) 2CO2(g) + 4H2O(l)
2(358+463+(414x3)) + (498x3) (804x2x2) + (463x2x4)
1300/2= -650 KJ/mole
Ethanol: CH3CH2OH(l) + 3O2(g) 3H2O(l) + 2CO2(g)
346+358+463+ (414x5) + (498x3) (804x2x2) + (463x2x3)
5994-4731= -1263 KJ/mole
Note: Combustion values are not exact to the book due to different values of bond energies.
Methanol: Inhalation and ingestion may be fatal. Inhalation also causes low blood pressure, headache, nausea, vomiting, dizziness, narcosis, central nervous system depression and suffocation. May irritate skin and eyes and temporarily damage corneas. Ingestion may cause blindness, vomiting, headaches and dizziness.