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

Comparing the enthalpy changes of combustion of different alcohols.

Extracts from this document...


COMPARING THE ENTHALPY CHANGES OF COMBUSTION OF DIFFERENT ALCOHOLS Analysis Results Table Alcohol Initial Temperature (c) Final Temperature (c) Initial Mass (g) Final Mass (g) Methanol 20 35 188.36 186.40 Ethanol 20 35 233.92 232.31 Propan-1-ol 20 35 244.67 243.24 Butan-1-ol 20 35 213.54 212.29 Pentan-1-ol 20 35 195.44 194.46 Hexonal 20 35 217.38 216.66 Alcohol Mass Loss (g) Relative Formula Mass Number of Carbon Atoms Methanol 1.96 32 1 Ethanol 1.61 46 2 Propan-1-ol 1.43 60 3 Butan-1-ol 1.25 74 4 Pentan-1-ol 0.98 88 5 Hexonal 0.72 102 6 Calculations The first step I need to take in calculating the amount of heat absorbed by the water in each experiment is to find out how much energy is transferred to the water to raise its temperature. ...read more.


= / 1000 for kJ = 205.71 kJ mol-1 (2.d.p) Table for all enthalpy changes Alcohol Moles Enthalpy Change (kJ mol-1) Methanol 0.06125 205.71 Ethanol 0.03500 360.00 Propan-1-ol 0.02383 528.75 Butan-1-ol 0.01689 746.00 Pentan-1-ol 0.01113 1132.08 Hexonal 0.00758 1662.27 Conclusion As my graph shows, as the number of carbon atoms in the alcohol molecules increase, so does the enthalpy change of combustion. This is because the more carbon atoms, and therefore hydrogen bonds, that the molecule possesses, the more energy is needed to break the larger amount of bonds. Evalutation I am pleased with my experiment as it returned results to confirm my prediction. I did not observe any anomalies which suggests that the results were accurate in relation to each other (suggesting that there were no human errors) ...read more.


9. The size of the wick. 10. Not all of the water was the same temperature. 11. The flame size changed due to the type of alcohol, hence it was a different distance away from the beaker each time. I could obtain a better picture of how the number of carbon atoms affects the heat of combustion in two ways. 1. I could extend my current experiment by testing other alcohols such as heptanol or octanol as well as by doing more repeats to increase the accuracy of my results. 2. I could conduct a similar experiment with other homologous series of hydrocarbons such as the alkanes or the alkenes. This would allow me to compare the results from each experiment and compare how the number of carbon atoms in the chain affects the heat of combustion. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level 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 AS and A Level Organic Chemistry essays

  1. Marked by a teacher

    Comparing the enthalpy changes of combustion of different alcohols

    3 star(s)

    The calculation for the energy released: Energy released (J/g of fuel) = energy transferred to water (J) � mass of fuel burned (g) Ethanol: Energy released (J/g of fuel) = energy transferred to water (J) � mass of fuel burned (g)

  2. Peer reviewed

    An investigation into the efficiency of alcohols as fuels.

    5 star(s)

    Their only purpose was to light the alcohol burner. The retort stand was set upon a heatproof mat to stop and conduction and damaging of the surface below it.

  1. The aim of this experiment is to investigate the enthalpy change of combustion for ...

    * Measure out 50cm3 of water using a bulb pipette as this is much more accurate than a measuring cylinder. Weigh the mass of the calorimeter then place the water into it and record the final mass, the difference between the two values should check that there actually is 50(g)

  2. Comparing the enthalpy change of combustion of alcohols down a homologous series.

    All the results were 30% (� 1%) of the actual results from the text book. From the graph it can be seen that the result for butanol was an anomalous result as it does not fit on the line of best fit as the rest of the results do.

  1. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    I am making sure that the amount of water is the same all the time so there will be no difference in my measurements due to volume. This would affect the experiment, as the energy that will be measured is heat energy transferred to the water and with a larger

  2. The Relationship Between The Number of Carbon Atoms In An Alcohol And Its Standard ...

    It would be much better if I were able to use the same size burner. If time permits, I shall repeat each of the experiments. Prediction My prediction is the fact that there will be a strong, if not definite correlation between the amounts of carbon atoms there are in the alcohol and its enthalpy change of combustion.

  1. Comprehensive and Detailed Chemistry notes

    cleaners identify that indicators such as litmus, phenolphthalein, methyl orange and bromothymol blue can be used to determine the acidic or basic nature of a material over a range, and that the range is identified by change in indicator colour -- Chemists have developed a wide range of synthetic acid-base

  2. Compare the enthalpy changes of combustion of different alcohols

    This also makes the total enthalpy change higher as the number bonds that need to be broken and formed increases. I predict that as the carbon chain increases then the enthalpy change of combustion will also increase. I can use the enthalpy change of alkanes to find a relationship with the enthalpy change of alcohols.

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