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

To find how much energy is produced when burning different alcohols.

Extracts from this document...

Introduction

Heat of combustion Aim I Aim to find how much energy is produced when burning different alcohols. To do this I will heat a beaker of water by burning alcohols. I will burn five different alcohols, methanol, ethanol, propanol, butanol and pentanol. I will also use these results to predict the heat of combustion of hexonal. Prediction I predict that all the experiments will be exothermic. This is because there are more bonds formed that there are made and bond forming is an exothermic process. I think that the more carbon atoms each alcohol has the higher energy per mole the more heat given out Theory The reaction that is involved in burning alcohols is exothermic because heat is given out. The formulae of the alcohols that I will be using are... � Methanol C1H3 OH � Ethanol C2 H5 OH � Propanol C3 H7 OH � Butanol C 4H9 OH � Pentanol C5 H 11OH Amount of bond energy C-H 413 C-O 358 O-H 464 O=O 498 C=O 806 C-C 347 Type of alcohol Energy required Methanol 2100 Ethanol 3270 Propanol 3740 Butanol 4560 Pentanol 5380 Methanol Balancing equations 2 C1H30H +3 O2 -> 2 CO2 + 4 H2O Diagram of compound C-C = 0 O-H = 1 C-H = 3 O=O = 3 C-O = 1 C=O = Apparatus Alcohols, methanol, ethanol, propanol, butanol, pentanol. ...read more.

Middle

Energy evolved in (kj) Methanol 21 000 21 Ethanol 21 000 21 Propanol 21 000 21 Butanol 21 000 21 Pentanol 21 000 21 To find out how much energy is produced per gram we use the formula... Energy per gram of fuel = Energy evolved x Mass of fuel burnt Energy per gram of fuel = 21kj x ? Below is a table showing how much energy is produced per gram when burning the alcohols in question... Type of alcohol Energy per gram (kj) Methanol 9.63 Ethanol 5.36 Propanol 4.16 Butanol 2.76 Pentanol 2.19 As you can see the energy per gram decreases as the length of the molecule increases. This is because more fuel is burnt so there is more of it to be filled with the energy. This is shown in graph 1. To find out how much energy is produced per mole you have to use this formula.. Energy per mole = Energy per gram x Formula mass Here is a list comprising all the formula masses of the chosen alcohols... � Methanol 32g � Ethanol 46g � Propanol 60g � Butanol 74g � Pentanol 88g Below is a table showing the energy produced per mole... Type of alcohol Energy per mole(kj/mol) Methanol 308.16 Ethanol 245.56 Propanol 249.60 Butanol 206.46 Pentanol 192.72 Again the results decrease as the molecule length increases suggesting that during the experiment more energy was last in the longer alcohols, this is shown in graph 2. ...read more.

Conclusion

This would give a better graph reading and a wider range of results to support a firm conclusion. On the other hand, if I had started below room temperature, so that the amount of energy gained, from room temperature might equal the energy lost at temperatures higher than room temperature. Next time reducing heat lost would be my main priority. Improving insulation techniques would be a valuable asset in obtaining the most reliable data I could. Another error is that of incomplete combustion. Complete combustion occurs if there are lots of oxygen atoms available when the fuel burns, then you get carbon dioxide (carbons atoms bond with two oxygen atoms). If there is a limited supply of oxygen then you get carbon monoxide (each carbon atom can only bond with one oxygen atom). This is when incomplete combustion has occurred. This is so because the carbon monoxide could react some more to make carbon dioxide. If the oxygen supply is very limited then you get some atoms of carbon released before they can bond with any oxygen atoms. This is what we call soot. Since heat is given out when bonds form, less energy is given out by incomplete combustion. So this is why it affects the outcome of the experiment. To overcome this problem, I would have to make sure a sufficient supply of oxygen was involved in the reaction. This could also be improved by making a better draught proof Chrissie Cassley 10E2 02/12/01 ...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. How Does The Increase In The Length Of The Carbon Chain Affect The Energy ...

    22�C 22�C Temperature at end. 91�C 88�C Temperature rise. 69�C 66�C Average rise, 69 + 66 = 67.5 2 Molecular masses, Butanol, 74 Ethanol, 46 Butanol heat given out = 20 * 4.2 * 55 = 4620 actual result, 2673 Ethanol heat given out = 20 * 4.2 * 66

  2. THE LINK BETWEEN CARBON ATOMS IN A FUEL AND THE ENERGY IT RELEASES.

    * In higher temperatures, heat is lost faster. * In the alcohols that have higher carbon, atoms experienced a lack of oxygen to react with, causing incomplete combustion in them. * If the alcohol available for the wick to burn were not enough, then the wick would burn not the alcohol, which would give an inaccurate result.

  1. To determine which alcohol, out of ethanol and propanol, is the better fuel. By ...

    The change for one mole can be worked out by (Energy ? / ?) x Mr of alcohol. Where ? is the loss of mass of alcohol and Mr is the molecular mass.

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

    Thermometer = (0.5 x 100)/100 = 0.5% 3. Measuring cylinder = (0.5 x 100)/100 = 0.5% 4. Ruler = (0.05 x 100)/160.5 = 0.31% From these calculations we can see that the thermometer and the measuring cylinder had the largest percentage error, closely followed by the ruler. The most significant piece of apparatus in causing any discrepancy of results would be these two.

  1. Find out how much energy is required to burn methanol, ethanol, propanol and pentanol, ...

    x 5 435 x 5 (O-H) x 1 464 x 1 (C-O) x 1 358 x 1 (O-O) x 3 497 x 3 (C-C) x 1 347 x 1 = 4835kJ mol-1 Bonds Made (C=O) x 4 802 x 4 (O-H) x 6 464 x 6 =5996kJ mol-1 Total Energy Released: 1161kJ mol-1 Propanol CH3CH2CH2OH + 4.5O2 --> 3CO2 + 4H2O Bonds Broken (C-H)

  2. Molar Heat of Combustion of Alcohols

    9870/0.58=17017 17017*60 Heat transferred to the copper calorimeter by burning one mole of propanol. 1021020J Table to show our results more clearly Ethanol Propanol Butanol Test 1 488 kJ Test 1 1021 kJ Test 1 1332 kJ Test 2 608 kJ Test 2 604 kJ Test 2 1813 kJ Test

  1. Investigate the different amounts of energy given off when different alcohols are combusted. I ...

    I can also work this prediction out using bond energies. I expect these bond energy results to show negative results, which means that the experiment is exothermic and is giving out heat. Although I know I must appreciate that my results will not be entirely accurate as heat will not completely be transferred to heating the water.

  2. GCSE Chemistry Revision Notes - everything!

    It turns damp blue litmus paper red. Water Water turns white anhydrous copper (II) sulphate powder blue and blue cobalt chloride paper pink. Flame tests A platinum (or nichrome) wire is dipped into concentrated hydrochloric acid and when held to a Bunsen flame. This step is repeated until the wire does not impart any colour to the flame.

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