• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10

How much Energy is Released from the Combustion of Various Alcohols

Extracts from this document...

Introduction

How much Energy is Released from the Combustion of Various Alcohols Aim To investigate how much heat energy is released when various alcohols (methanol, ethanol, propan-1-ol, butan-1-ol, and pentan-1-ol) combust. SCIENTIFIC BACKGROUND AND PREDICTION Scientific Background of Alcohols Methanol, ethanol, propan-1-ol and butan-1-ol are part of the alcohol homologous compound series, which is defined by their function group of -OH. Below is the structure of ethanol: The general formula for alcohols is CnH2nn+1OH. As I have proved earlier on in my prediction, larger alcohol chains have release more energy when combusted because they have more bonds, but this also means they have a higher boiling point: Alcohol Formula Boiling point (oC) Methanol CH3OH 65 Ethanol C2H5OH 78 Propan-1-ol C3H7OH 97 Butan-1-ol C4H9OH 117 Pentan-1-ol C5H11OH 137 Ethanol burns with the following equation: Ethanol + oxygen ==> carbon dioxide + water 2CH3OH + 3O2 ==> 2CO2 + 4H2O This means that the burning of an alcohol (in this case ethanol) releases only carbon dioxide and water, which are environmentally friendly products so alcohols as fuels are environmentally friendly. The production of alcohol is also easy. It can be fermented: Glucose ==> ethanol + carbon dioxide Which is environmentally friendly or through the hydration of ethene: C2H4(g) + H2O(g) C2H5OH(g) Prediction I believe that larger chains of alcohol (e.g. propan-1-ol) will combust to release more heat per a mol than a shorter chain of alcohol s(e.g. ethanol). Scientific basis I believe this because using bond energies we can find out the energy stored in 1 mol or reactant and see how much energy is lost (endothermic reaction) ...read more.

Middle

The container should be as close to the wick as possible. The can will be placed just above the tip of the flame. Starting temperature of water: This should be similar all the way through, because of factors leading to evaporation of water due to higher temperatures. This should not matter too much as room temperature should remain constant. This cannot be changed and is not very significant either. Draft shields: Can affect how much heat gets to the container. A draft shield will be used. Stirring: Stirring the water in the can makes the water heat up faster. Therefore stirring can affect the results obtained. The cans should be stirred at a constant rate throughout the heating. Safety Safety goggles were worn throughout the experiment. Care was taken not to ingest the alcohol. Diagram Method The apparatus was set up as above. The starting temperature of the 250ml of water was noted. The water was put into an aluminium Coke(tm) can. The spirit burner was weighed with its cap on and then put under the can so that the tip of the flame was just touching the bottom of the can. The cap was taken off and the wick lighted as soon as possible (so that the alcohol would not evaporate). During the heating of the water, the water was stirred at a constant rate so that it would heat the water evenly and the water would heat up faster. Once the water reached 20oC above it's starting temperature (usually around 42oC), the flame of the spirit burner was blown out, the cap replaced and weighed again as quickly as possible. ...read more.

Conclusion

This meant that a fast burning spirit burner would use more alcohol to heat the water up by 200C than a slow burner. This could be corrected by using the same spirit burner for every alcohol. * At the bottom of the can was carbon, which showed incomplete combustion and insulated the water from the heat of the burner. This meant that not all of the alcohol was being combusted to produce heat, carbon dioxide and water, some was also producing carbon. This also meant that an insulator had been formed and results after the first experiment would be inaccurate as a result. This could be corrected by using a different can for each experiment so there would be no insulating carbon layer at the start. * Alcohol was still lost after the initial weighing and before the final mass weighing through evaporation, as sometimes, due to disorganisation, the wicks were not lighted immediately after the mass reading had been taken. This meant that some of the results were inaccurate. Ensuring organisation and keeping a ready supply of spills and a burning Bunsen on the table could correct this. * Stirring was not entirely accurate due to human error. This meant that when the water was being stirred faster the water heated up faster and less alcohol was combusted than should have been. This could be corrected next time by not stirring the water at all (but this would take a long time for the water to heat up) or using a machine to stir the water at a constant speed. * Some of the heat from the burner was lost to the surroundings. This cannot be corrected. * * * * Chemistry coursework DeveshPAREKH 1 ...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. Marked by a teacher

    Experiment to investigate the heat of combustion of alcohols.

    4 star(s)

    Y/X x Mr Joules Finally, to convert the result into kilojoules, divide the answer by 1000, converting the result into kJ/mol. Methanol > 3.01g produces 16800 joules > 1g produces 16800/3.01 joules = 5581.40 Joules. > 1 mole produces (16800/3.01 joules)

  2. Investigating the Combustion of Alcohols

    OBTAINING EVIDENCE 1) The calculation of the enthalpy change of combustion for methanol is carried out as shown below, based on the following assumptions: Volume of water = 75cm3 Temperature rise = 25� C Specific Heat Capacity of water = -4.2 J g-1 K-1 Mass of alcohol burned = 1.06g

  1. Energy Released From the Complete Combustion of Different Alcohols

    of the can and using 300 cm3 of water may cause the metal can to fall; because of the heavy weight. 7- Measurements: * I am going to measure the initial and the final reading of the spirit burner in order to get the mass of fuel consumed.

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

    the number of carbon atoms in the chain increases the enthalpy change of combustion becomes more negative. This graph shows the relationship between the enthalpy change of combustion and the number of carbon atoms. In order to keep this particular graph simple I have only used propan-1-ol and butan-1-ol and have left out propan-2-ol and butan-2-ol (the isomers).

  1. Molar Heat of Combustion of Alcohols

    Conduction would be a relatively minor problem. The copper calorimeter will conduct some energy to the clamp stand but the test tube and the beaker are both glass and do not conduct the heat as well. Radiation could be reduced by using insulation and a lid for the beaker.

  2. A Comparison of the Energy Released When Different Fuels are burned.

    8 x 805 = 6440 10(H-O) 10 x 464 = 4640 + 11080 KJ/mol H = Sum of �E broken - sum of �E formed = 9363 - 11080 = -1717 KJ/mol H is negative; therefore the reaction will be exothermic * Pentanol Pentanol + Oxygen carbon dioxide + water C5H11OH + 71/2O2 5CO2 + 6H2O Sum of bond energies broken: 11(C-H)

  1. The Energy Content Of Different Fuels

    that the heat has to travel the same distance for each time. * Repeat all of this 3 times so that you can average out all the results for each fuel, to make it a more accurate way of finding the results.

  2. GCSE Chemistry Revision Notes - everything!

    Sodium carbonate is sold as washing soda and is effective as a degreasing agent. Metal Hydroxide Chloride Sulphate Nitrate Carbonate Lithium LiOH LiCl Li2SO4 LiNO3 Li2CO3 Sodium NaOH NaCl Na2SO4 NaNO3 Na2CO3 Potassium KOH KCl K2SO4 KNO3 K2CO3 Group 2 Group 2 are all metals with low melting points and densities.

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