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Enthalpy of Combustion of Alcohols

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Chemistry Coursework Investigation Enthalpy of Combustion of Alcohols Procedure 1. Put 150� of cold water in an aluminium calorimeter and record its temperature. 2. Support the calorimeter over a spirit burner containing the ethanol you are going to burn. Arrange a suitable draft exclusion system to reduce heat loss. 3. Weigh the burner and Alcohol. 4. Replace the burner under the calorimeter and light the wick. 5. Stir the water with a thermometer. 6. When the water temperature has risen by between 15 and 20�C extinguish the burner but continue to stir it until the temperature stops rising. Record the highest temperature reached. 7. Reweigh the burner to find the mass of the alcohol that has been burned. 8. Repeat the experiment at least once more. 9. Now repeat the whole experiment 2 times but you have to use Methanol the first time and Butanol the second time instead of Ethanol. Aim: The aim for this experiment is to find the Enthalpy of combustion of 3 different alcohols Ethanol, Methanol and Butanol by doing that I'm going to prove my theory. How I will collect valid results in my planned experiment I am planning was to do the experiment I will be very carfully in following the procedure ...read more.


kj Energy Released per mole of Methanol burned 108829.1125 kj 112423.924 kj 121191.532 kj Results for Butanol Mass of Beaker 78.71g 1 2 3 Mass of water 150.28 g 150.89 g 148.2 g Initial temp of water 22.60 C 22.90 C 22.5 C Final temp of water 43.1 C 43.4 C 43.7 C Temperature rise 20.5 C 20.5 C 21.2 C Mass of burner initially 183.59 g 181.60 g 179.38 g Mass of burner finally 181.60 g 179.38 g 176.84 g Mass of Butanol burned 1.99 g 2.22 g 2.54 g RFM of Butanol 74 74 74 Moles of Butanol burned 0.02689 g 0.03 g 0.0343 g Energy released 12939.108 kj 12991.629 kj 13195.728 kj Energy Released per mole of Butanol burned 48118.661 kj 433.054 kj 384715.102 kj Difficult Calculations about alcohols Example Butanol Moles of Butanol burned=Mass of Butanol burned RFM of Butanol Energy released= m x c x?T (Mass of water x 4.2 x Temperature rise) Energy released per Energy released Mole of Butanol burned= Moles of Butanol burned Diagram of the Experiment Equipment to use -200ml aluminium calorimeter -500ml plastic calorimeter -Thermometer -Fuel-burner -Triangle-stand -Heatproof mat -Fire Resistant underground -Safety goggles -impervious clothing -gloves -Respiratory protection May be required Materials to use -100ml of Ethanol -100ml ...read more.


Structural Formula: Bond Braking Bond Forming Bond Number Energy Bond Number Energy C-C C-H C-O O-H C=O O=O C-C C-H C-O O-H C=O O=O Total energy used= Total Energy released= Overall energy change= Enthalpy of Combustion of Butanol Balanced Equation 2C4H7OH + 12O2-----------8C02 + 10H2O Structural Formula: Bond Braking Bond Forming Bond Number Energy Bond Number Energy C-C C-H C-O O-H C=O O=O C-C C-H C-O O-H C=O O=O Total energy used= Total Energy released= Overall energy change= Evaluation I believe that the procedure which I used was very good and I obtained very good evidence with my simple procedure.I had 1 anomili in my second reading for Butanol but I did a third reading I think my results were relieable because I didn�t have many anomalis but I believe that this experiment was not as accurately as it could have been because: 1:Because of the Heat loss on the top and side on the beaker. 2:Incomplete Combustion 3:There is heat which never arrives at the beaker because of winds. 4:That not all the water was the same temperature. I could have improved my results by isolating the the beaker from the top and the sides I could have build a wall where no wind would have gone through. ...read more.

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