Chemistry - Reactivity Serires report
4 star(s)
Methanol - Bond Energy Calculations
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Introduction
Methanol Bond Energy Calculations: Methanol + Oxygen � Carbon dioxide + Water 2CH3OH + 3O2 � 2CO2 + 4H2O = 2 moles of Methanol Structure of Reactors: 2x 6x H H - C - O - H O = O H = H - C x 6 (435) C - O x 2 (358) O - H x 2 (464) O = O x 3 (497) = 5745kj Products: 4x 2x H - O - H O = C = O = C = O x 4 (803) O - H x 8 (464) = 6924kj ?E = 5745kj - 6924kj = -1179/2 = -589.5 kHz/mol Ethanol Bond Energy Calculations: Ethanol + Oxygen � Carbon dioxide + Water C2 H5 + 3O2 � 2CO2 + 3H2O Structure of Reactors: H H H - C - C - O - H H H = H - C x 5 (435) C - O x 1 (358) O - H x 1 (464) O = O x 3 (497) C - C x 1 (347) = 4835kj Products: 2x 3x O = C = O H - O - H = C = O x 4 (803) O - H x 6 (464) = 6996kj ?E = 4835 - 6996kj = -1161 = -1161 kj/mol Propanol Bond Energy Calculations: Propanol + Oxygen � Carbon dioxide + Water 2CH5H7 ...read more.
Middle
This also applies for the fuel to be burned obviously that has to be changed. First, I plan to experiment with the amount of water to be heated in order to gain the clearest temperature difference results. I plan to experiment with 3 different amounts of water; 25, 50 and 75 ml. because I am using 1ml of fuel I am unable to use a beaker other than one that is of 100ml volume due to the fact that a larger beaker would require more than 75ml water in order to submerge the bulb of the thermometer. The results were as follows:- Fuel - Methanol 25ml 50ml 75ml 1 2 1 2 1 2 Start Temp. 21?C 29?C 29?C 27?C 28?C 24?C 23?C This clearly shows that the biggest change in temperature was using 25 ml of fuel, consequently I will use this amount as I believe it will give me the clearest results as well as submerging the bulb of the thermometer. Although I am unable to test any other variables I have thought about them and noted my reasons for particular ones below: Due to the way I will carry out my experiment (see below) I have decided to use a 10 cm diameter watch glass in which to place my fuel for burning, this is because there is a larger surface area for the ...read more.
Conclusion
Also my apparatus is chosen as it is safe, both water and fuel would be hard to spill and the fuel will also be lit safely. Lastly whilst carrying out all experiments in the laboratory I shall stand, enabling me to move quickly if needed. Overall the main safety hazards are getting burnt or by spilling alcohol over bare skin. Prediction: My prediction is based on the molar energy calculations; I have calculated the following. Energy Released per 1 ml Methanol: = -589.5 kj/32g =-18.42 x 0.793 = 14.60j Ethanol: = -1161 kj/46g =-25.24 x 0.789 = 19.91j Propanol: = -1732.5 kj/60g =-28.88 x 0.804 = 23.22j Butanol: = -2304 kj/74g =-31.14 x 0.810 = 25.22j Pentanol: = -2875.5 k/j80g =-32.68 x 0. 815 = 26.63j This shows me that he higher the bond energies the more transferral of heat will take place, due to the increased number of breaking bonds. Also because I am measuring the fuel by ml there are different densities. Therefore effectively there is more Pentanol than Methanol. In short, due to the more carbon atoms the alcohol compound has a higher bond energy and subsequent heat transferral. Task: To investigate how the combustion of 1ml, of at least four alcohols raises the temperature of a particular amount of water. Results: Four tests for each fuel and the average temp rise Fuel Exp. 1 Exp. 2 Exp. 3 Exp. 4 Temp Rise Methanol Ethanol Propanol Butanol Pentanol ...read more.
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