• 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...


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.


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.


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. 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.

  1. Comparing Energy Given When Different Alcohols Burn.

    of the calorimeter and the top of the wick ma be closer which will cause greater heat loss than there already is. Therefore I will measure the wick to make sure it is the same length, it will be 0.5cm taller than the mini beaker therefore it is 3.0cm.

  2. Comparing the heat energy produced by combustion of various alcohols

    The temperature Because during heating the water, there may have some water evaporate to the air, so therefore the volume of the water wouldn't be accurate. 2) The heat of energy given from the alcohols The reason of this happen which is because the condition in the lab may change,


    From the graph, my line of best fit started from the origin and touched nearly all the point through the graph; the ones that weren't exactly on the line were very close to it. This also shows that when x= 0, y =0 because there is no carbon atom, there

  2. Energy Released From the Complete Combustion of Different Alcohols

    of "OH" is in each type of alcohol is 17, since the mass number of hydrogen is 1 and the mass number of oxygen is 16 therefore, 16+ 1 = 17. Burning fuels is an exothermic reaction, because there is heat released and the total energy released in bond formation is greater than that energy needed for bond breaking.

  1. Investigating the energy released from burning different alcohols.

    Planning I plan to use an alcohol burner to heat up 100g of water until it rises 10oC in temperature. I will measure the mass of the alcohol burner before and after the combustion, from these values I will calculate how much of the alcohol was used to raise the

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

    x 1 358 x 1 (O-O) x 1 497 x 1.5 =2872.5kJ mol-1 Bonds Made (C=O) x 2 802 x 2 (O-H) x 4 464 x 4 =3462kJ mol-1 Total Energy Released: 589.5kJ mol-1 Ethanol CH3CH2OH + 3O2 --> 2CO2 + 3H2O Bonds Broken (C-H) x 5 435 x 5 (O-H)

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