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

Investigate the heat energy in a range of alcohol's used as fuels.

Extracts from this document...



Investigate the heat energy in a range of alcohol's used as fuels.

I predict that octanol will release the most heat energy. This is because there is more bond energy in that molecule than the other alcohols.
Within a molecule there are bond energies that are holding the atoms together. When the fuel combusts a chemical reaction takes place, this breaks the bonds, this requires energy, and makes new bonds this gives out energy. The energy differences between the two tell us how much energy was given out or taken in. We can show this on a graph.

To find the bond energies in the molecule of the alcohol we have to look at the how much energy is in the separate bonds of the molecule. Below we have a table of bond energies

Bond Bond Energy (kj/mol)
C - OH 402
C - H 435
C - C 347
H - O 464
C = O 805

If we draw out the structure of each molecule involved in the chemical reaction we can easily find out how much energy is in that molecule.













...read more.


2C4H7OH + 12O2(r) 8C02 + 10H20

2C5H9OH + 15O2(r) 10C02 + 12H20

2C6H11OH + 18O2(r) 12C02 + 14H20

2C7H13OH + 21O2(r) 14C02 + 16H20

2C8H15OH + 24O2(r) 16C02 + 18H20

We can see from the table above Octanol releases the most heat energy. This clearly shows that there is a correlation between the number of bonds in the molecules and how much total energy was released.
I also predict that the amount of heat energy released will increase with the number of carbon atoms in the alcohol. The equation for working out the energy released is:

Heat released = (-574 x No. of carbon atoms) x 2024

To keep this a fair test we have to bear certain aspects in mind. The beaker the water is contained in must be the same shape because if it is not the flame may have more surface area of where to heat the water. The alcohol must be weighed accurately with scales that weigh up to, least, one decimal point. During weighing the spirit lamp must be covered to avoid and evaporation of the alcohol.

...read more.


The results I got from my experiment were accurate enough to give me results I can relie on. I could have got more accurate results by modifying my plan for my experiment. When I was carrying out my experiment I saw four main things that could be improved to make the results more accurate.
1. Heat which never enters the water, because of draughts, for example.
2. Heat loss from the top and sides of the beaker.
3. Heat which is not conducted by the beaker.
4. Incomplete combustion - there is a restricted supply of oxygen, the alcohol was burning with an orange flame rather than blue. Some of the alcohol did not burn completely, giving carbon and carbon monoxide rather than carbon dioxide. A carbon deposit (soot) on the bottom of the beaker indicated this.

Improvements can be made to this by insulating the sides of the beaker, using a different material for the beaker, using a lid a providing a draught screen as shown below.

Alternatively we can remove all faults in planning by using an advanced technique such as a bomb calorimeter. This is the most accurate way of measuring bond energies and this will be as accurate as we can get in our results.

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism 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 Electricity and Magnetism essays

  1. Marked by a teacher

    Investigation into Energy Released From Burning Various Alcohols.

    4 star(s)

    I will also let the flame on the burner burn for 30 seconds before placing it beneath the beaker of water. This will allow it to stabilize, and the alcohol will be burning at a constant rate. When I measure the mass of the spirit burner, I will measure it with the cap on.

  2. To investigate which fuel gives out the most energy when burnt. We are burning ...

    1 X C-O (1 X 360) 1 X O-H (1 X 460) 41/2 X 0=0 (41/2 X 496) 2 X C-C (2 X 350) = 6622KJ/MOL Bonds Made 6 X O=C (6 X 740) 8 X O-H (8 X 460) = 8120KJ/MOL Energy released- 8120 + 6622 = -1498KJ/MOL _ _ _ _ _ _ _

  1. "My aim is to find out how much energy is released when burning different ...

    The temperature increase has turned out very high compared to the other crisps, but this is probably because it has a higher fat content than the rest. The equation to find out how much ENERGY RELEASED from 100g of crisp.

  2. Measuring the specific heat capacity of water

    P = M x C / T P = M x C x Gradient2 C = P / M x Gradient C = 12 /(0.425 x 0.0066666667) C = 4235 j/kg�C Conclusion From my calculation and results I have obtained the Specific Heat Capacity of water to be 4320 j/kg�C for this practical.

  1. Finding a material's specific heat capacity

    As many repeats as possible will be made. * Finally, the mass of the copper block will be recorded after measuring it with an accurate electric balance. Once all the data has been collected, it will be tabulated. Average percentage errors will be calculated for all measurements and figures quoted.

  2. Investigating the heat of combustion of a series of Alcohols

    Results Table Alcohol Temperature of water at start (oC) Highest temperature of water (oC) Temperature change Mass of alcohol Used (g) Ethanol 19 29 10 0.5 Propanol 19 29 10 0.5 Butanol 19 29 10 0.5 Pentanol 19 30 11 0.5 Hexanol 19 30 11 0.5 Energy transferred in the experiment I expect the total amount of energy for

  1. Identifying the science involved in nuclear fusion and is it the energy for the ...

    = 1.6 � 10-13 Joules Therefore 17.59 MeV = (17.59 � 106 ) � ( 1.6 � 10-13 )

  2. Renewable and non-renewable fuels

    into the reservoir at times when there is more electricity available on the distribution network than there is demand, this is comparable to a large battery to store power until it is required. There are other advantages, the control of large amounts of water in a reservoir can prevent mass

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