• 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 Introduction The enthalpy change of combustion of a fuel is a measure of the energy transferred when one mole of the fuel burns completely. A value for the enthalpy change can be obtained by using the burning fuel to heat water. In this experiment I will be calculating and comparing the enthalpy changes of combustion of 5 different alcohols. I can calculate the enthalpy change by using the information that 4.2J of energy is needed to raise the temperature of a 1g of water by 1�c. I will heat a measured volume of water using a fuel burner to change its temperature by 15�C; then I will find the mass of the fuel that has been burnt. With this information I will be able to calculate the amount of energy in 1g of the fuel used. I will then plot my results into a graph, in order to compare them and to allow the pattern to become more apparent. Equipment * The apparatus required to carry out this experiment are as follows: * Heat proof mats (x6) * Clamp stand * Calorimeter * Fuel burners (containing Ethanol, Methanol, Propan-1-ol, Butan-1-ol, and Pentan-1-ol) * Scales * Water * Splints * Bunsen burner * Parcel tape * Thermometer * Calorimeter lid * Measuring cylinder * Scouring pad * Emery paper. ...read more.


When the fuel burner was being carried to and from the scales, extra care was taken to make sure that it was not dropped and broken. Stock bottles of alcohol were kept away from naked flames so they could not catch light. Fair Test There were a number of things we had to control to make sure our experiment was a fair test. To begin with, in our groups which we worked in to gather the data, we allocated each other specific jobs, so that we became 'specialized' and so even if there were mistakes in our technique, the mistakes were repeated throughout all the experiments and so the end result should be the same, reducing the chance of overall error and inaccuracy. We also used the same calorimeter each time we did our experiments. This was because a slight difference in the weight of each calorimeter was noticed, and therefore a different density; which would affect their ability to conduct heat, and so the same calorimeter would need to be used each time to make the experiment a fair test. We also noticed that different scales could give different results, and so we used the same set of scales each time. The water used was always taken from the tap, and so although it contained impurities, all the experiments were performed using this water, so the accuracy of the experiment was not at risk. ...read more.


With less bonds being formed than broken then energy is given off, and if the ratio is increased further, then even more energy is given off. Evaluation There were a number of sources of error in my experiment. For example, much of the heat given from the fuel would have been lost because the calorimeter was placed 13cm away from the heat source, and although draft excluders were used some heat will have escaped. Also, because we were using alcohols, windows had to be opened for ventilation, which caused drafts which stopped all the energy being used to heat the water. It was left to human judgement, when the temperature had reached 15�C above the starting point, and so there could be error in the judgement. Another problem would be the build up of soot on the bottom of the calorimeter. Although this was cleaned after every run, it still became insulation to the water, stopping it from heating slightly. Also, the calorimeter which was used was heated slightly, and so energy was wasted by the heating of the calorimeter. The errors could have been reduced if an electric thermometer were used, and so a more accurate reading could have been gathered. Also, if the experiment was performed under more controlled conditions, where no energy could escape from heating the water then the experiment would give much more accurate results. Patrick Begley 2 ...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. Investigating the Combustion of Alcohols

    showing the trend between enthalpy changes of combustion of the different alcohols using different sources of information. Alcohol Experimentally determined Enthalpy Change of Combustion/ kJmol-1 Spreadsheet Enthalpy kJmol-1 Nuffield Databook Enthalpy Change of Combustion / kJmol-1 Methanol -254.0 -658 -726.0 Ethanol -381.3 -1276 -1367.3 Propan-1-ol -543.1 -1894 -2021.0 Butan-1-ol N/A

  2. Comparing the Enthalpy changes of Combustion of different Alcohols.

    x (mass of fuel used) = (1/60) x 0.70g = 0.0117 moles (4.d.p.) * Energy transferred by this number of moles: (Look above at bullet point number 4) 194.25g x 19.75oC x 4.2J = 16113.0375J * Energy transferred by 1 mole of fuel: 0.0117 moles = 16113.0375J 1 mole = (16113.0375/0.0117)

  1. hydrogen peroxide experiment

    Therefore if any further work was going to be carried out a change of method would be needed.

  2. Comparing the Enthalpy Changes of Combustion of Different Alcohols

    Different H-bonding iterations also have on effect on the ?Hc thus propan-1-ol and propan-2-ol have different ?Hc values. The method I am using is from the preliminary work I carried though many problems with my original method have been improved.

  1. Investigating the different amounts of heat given off by different alcohols in spirit burners ...

    = 463 1 x (C-C) = 348 3 x (O=O) = 1488 + = (+) 4719 Bonds Made: 4 x (C=O) = 2972 6 x (O-H) = 2778 + = (-) 5750 Total energy: (+) 4719 (-) 5750 = -1031 kJ/mol. Reaction is exothermic. Propanol: C3H7OH + 41/2 O2 --> 3 CO2 + 4 H2O Bonds Broken: 7 x (C-H)

  2. Comparing the enthalpy changes of combustion of different alcohols.

    -6932 kJmol-1 + 5616 kJmol-1 = -1316 kJmol-1. As in this equation there were two moles we must divide this by two. Therefore the answer is -658 kJmol-1. As I am using different data sources this will not be the same as the figure used in the calculations in the analysis.

  1. Investigation to compare the heat energy produced by combustion of various Alcohols

    This means the test will all be fair Prediction I think the more bonds in the alcohols molecule structure means that more heat energy will be produced when the bonds are broken and so less fuel will be used, as the heating temperature will be higher, so it will not take as long to heat.

  2. GCSE Chemistry Revision Notes - everything!

    Members of family have similar chemical properties and physical properties gradually from one member to another. Hydrocarbons are organic molecules, they can exist in chains, branched chains or in rings of carbon atoms with hydrogens attached. Crude oil is a mixture of hydrocarbons.

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