• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Alcohol Combustion Experiment Evaluation

Extracts from this document...


Alcohol Combustion Experiment Evaluation In comparing my results with those of published data, I found that my calculated heats of combustion were not accurate. However they did all follow the trend that published data showed, and in that respect my results were correct. The reasons behind why my results were inaccurate are mainly due to heat loss and incomplete combustion. However, if I were to conduct the investigation again, I feel that my results would be more accurate and closer to those of published data. This is because I now know why my results were inaccurate. One of the reasons behind why my results were inaccurate was due to heat loss. The fact that there was a sufficient heat loss meant that the temperature rise figure required to work out the energy of combustion was inaccurate. This inaccuracy affected the whole of the results, and would have been emphasised as I multiplied the number of kilojoules up to 1 mol. I could solve this problem by decreasing the distance between the burner and the water tin, as this would have reduced the heat loss, although by doing this some heat still would have been lost to the surrounding air. ...read more.


However, the stirring would have to take place in an enclosed beaker, as by stirring, you are increasing the rate of evaporation, which will eventually reduce the temperature of the water. Another cause of inaccurate results was the time taken to weigh the burner after combustion. Weighing must be done fast as the alcohol will evaporate as it cools done. This evaporation will gradually decrease the mass of the alcohol. Even if the decrease due to evaporation were minimal it would still have a massive effect on the final outcome. As explained above, there are many ways and reasons why my results were not as accurate as they could have been. Although they are not completely accurate, due to heat loss and incomplete combustion etc., I still feel that the evidence is sufficient to support the conclusion. This conclusion was that as the alcohols series declined, the heats of combustions increased. From my graphs and tables of results I can see that my findings support this. I think that my results were reliable. This is because they were all done under the same conditions. ...read more.


* There is a stirrer - this would enable that all of the water was being heated. * The water is enclosed - this would mean that minimal energy is lost to the surroundings. * There is a constant supply of oxygen - required for combustion If were to use the above equipment, I would expect the results to be closer to reality i.e. closer to those results in published data. This is because there is a better air supply, less of the energy is lost to the surroundings and the water is enclosed and stirred. Also, the above equipment would solve the problem of incomplete combustion so the results are more likely to be closer to published data. However, they would still not be exact as some heat will always be lost and complete combustion cannot always be ensured. There would also be the same weighing problems regarding the burners. If the burners are not weighed as soon as combustion is finished, the alcohols will continue to disappear through evaporation, which would gradually decrease. Even a slight decrease from the exact mass change would have a significant effect on my overall results. Owen Williams 11.3 Heat of Combustion Investigation Evaluation ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Organic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Organic Chemistry essays

  1. The Heat of Combustion of alcohol.

    of 0.75g Butanol - 200.13 199.54 = Change of 0.59g Pentanol - 206.24 205.70 = Change of 0.54g Energy Given = mass of water x 4.2 (SHC of water) x Temperature Change Out = 100 x 4.2 x 20 = 8400J Methanol CH3OH 0.96 of Methonal gives 8400J 1g 8400J 0.96 = 8750J 1 mol of methanol (32g)

  2. Molar Heat of Combustion of Alcohols

    thermometer can only be read to 1OC and even then could be read inaccurately. * Impurities in water (may change the specific heat capacity of water). * All results were conducted under different conditions. Not all of the alcohol was burnt effectively in the test.

  1. Investigate the enthalpy change of different alcohol

    1 mole of butan-1-ol: 74 > Number of moles of butan-1-ol used: 0.68/74 = 0.009189 mol (corrected to 6 decimal places) > Energy transferred by this number of moles of butan-1-ol: 13969.5J > Energy transferred by 1 mole of butan-1-ol: 13969.5J/-0.009189 mol = -1,520,187J/mol (corrected to the nearest integer)

  2. The Combustion Of Alcohol

    Also the water needs to fill the container fully, so that energy isn't lost by being transferred to the surroundings, rather than the water. Volume of water: If too much water is used I run the risk of getting to low a temperature increase for my thermometer to read however

  1. hydrogen peroxide experiment

    Then the amount of water needed will be measured out into another measuring cylinder. The two cylinders will then be poured into a third cylinder which will then be poured into the conical flask with side arm after the Manganese (IV)

  2. Chemistry Course Work: Combustion of Alcohols

    As the more bonds holding the Carbon, Oxygen and Hydrogen atoms together more the energy required to break these bonds. And of the 5 alcohols that we will be using, 'Hexan-1-ol' has the greatest number of bonds in its structural formula The heat produced per mole of alcohol molecules will

  1. Alcohol Combustion Experiment

    x 347 = +694 8 x H-O is 8 x 464 = -3712 1 x C-O is 1 x 358 = +358 1 x O-H is 1 x 464 = +464 4.5 x O=O is 4.5 x 498 = +2241 TOTAL = +6648 = -8542 Heat of Combustion = +6648-8542 ?H = -1894 kJ mol -1 3.)

  2. GCSE Chemistry Revision Notes - everything!

    In an increasing amount of countries, alcohol is being used as a fuel, as it only releases CO2 and H2O and not the pollutant gases of petrol. It is also renewable because it comes from plants. Production of ethanol Ethanol can be produced in two ways, either by fermentation or using ethene and steam.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work