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Combustion of alcohols

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Introduction

David Downs Combustion of alcohols I aim to investigate the heats of combustion in comparison to the number of atoms in the molecule between different alcohols. To do this I will heat some water in a beaker until it has risen in temperature significantly and then will weigh it in order to establish the change in mass thus to work out the heats of combustion. I will use the equation E=MC T and the specific heat of water (4200j) to calculate the heats. In this equation E is the energy required to raise the waters temperature to the specified heat (j), M is the mass of water in the beaker (kg) and C is the specific heat. is a Greek letter used in Chemistry to symbolise 'change in'. Therefore T is the change in temperature (?c). An alcohol is a water molecule with an alkyl group in place of one of the Hydrogen atoms. ...read more.

Middle

4. Note the starting temperature of the water. 5. Place the burner under the can and ignite it. 6. Monitor the temperature until it reaches the desired change and then extinguish the flame. 7. Re-weigh the burner once it has cooled (handling it only with the clasps at first) and then deduce the change in weight. 8. Repeat this for all 4 alcohol samples. (To improve the efficiency of the experiment changes could be made such as using a heat shield or coating the inside of the tin with heat resistant paint. However I have chosen not to employ these methods because of practicality and lack of materials even though they would undoubtedly improve the accuracy of the experiment.) Safety * Basic lab safety precautions should be observed while conducting any experiment. * When fire is involved special care is needed and all apparatus must be handled with caution and the correct equipment. * As most of the equipment is metal then the heat will conduct throughout the apparatus and so all parts must be handled with caution. ...read more.

Conclusion

The gradient of the graph re-enforces this, as it increases in gradient. The overall conclusions of this experiment agree with the facts laid down by the textbook Cambridge advanced sciences, Chemistry 1 and so can be assumed to be reasonably accurate. However the small errors that were made could be eliminated should the experiment be repeated. Errors such as the heat loss through the can. Introducing a heat shield or using a can made of a material with less heat conductivity could reduce this. If I were to require more accurate results I would conduct the experiment under such circumstances to give better results. However I think that the results I have obtained are sufficient to draw limited conclusions from and therefore are deemed adequate. However if I were to require more accurate conclusions more accurate results would need to be obtained form another experiment. Further experiments were not conducted due to lack of time. ...read more.

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