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

Comparing the Energy Released By combustion of Different Alcohols

Extracts from this document...




To investigate and compare the relationships between the amounts of energy released from different alcohols in the alcohol series.


Alcohols are a series of organic homologous compounds with the general formula of C(n) H(2n+1) OH. They gain their properties, which are different to those of other compounds in the homologous series due to the OH bonded to the Carbon. The 4 simplest alcohols are Methanol, Ethanol, Propanol and Butanol. Each alcohol has one more carbon and two more hydrogens than the previous one.

When alcohols are heated to react in a copious supply of oxygen they undergo complete combustion to form carbon dioxide and water. The reaction is an exothermic one and produces a flame emitting light and thermal energy. This is because the energy put into the alcohol to break the bonds is less than the energy given out by new bonds forming. Therefore, different alcohols release different amounts of energy. The diagrams and calculations on the following sheets show the theoretical energy release of each alcohol using the bond energy values below.










805 (Carbon dioxide)





The calculations show that: (the negative values mean energy is lost from the compounds and is therefore given out as heat or light)











...read more.



  • How high do I place the calorimeter above the burner?

I found that a decent sized flame was 4cm and therefore I clamped the calorimeter 7cm above the top of the burner. This allowed for the flame to burn freely without the bottom of the calorimeter interfering with the combustion and making it unfair.

  • How large should the flame be?

Although the size of the flame will not effct the results diretly because the rate at which the alcohol burns is irrelevant due to the fat that the change in mass is also measured. However, the size of the flame can make the results inaccurate in other ways. I found that the small flames flickered to much and did not produce a constant enough source of heat. However, I also found that the large flames were blown around a lot by the slightest of drafts and therefore the heat was not always being transferred into the calorimeter. I decided that 4cm was a good height to use as it was not affected by the drafts too much and did not flicker.

  • How much water do I fill the calorimeter with?

The amount of water in the calorimeter needs to be a sensible amount as too

...read more.


The results support my prediction in the way that I predicted that as the length of the chain increased so to would the energy released. However, I also predicted that the graph would show directly proportional results, which it does not. My prediction also stated that the results would be lower than the theoretical values due to heat loss which proved to be correct.


I believe the method I used was as accurate as possible with the equipment provided, although the results do not show this. The energy released per mol values are a lot lower than the theoretical values due to heat loss. Because of the large amount of heat loss the results are quite varied and unreliable. I only encountered one anomalous result, which is highlighted in red on the results table. I believe this is because of less heat being lost during this test than the was lost during the other tests for propan-1-ol. To overcome this problem barrier could be placed around the burner to shield it from drafts and guide the heat towards the calorimeter.

I believe that the results show a curve because more heat was lost for the small-chained molecules due to the lower temperatures of flame being blown away more easily than those flames with higher temperatures.

...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)

    539.5 Ethanol 1040.0 Propan-2-ol 1540.5 Butan-1-ol 2041.0 Pentan-1-ol 2541.5 This data was obtained in the following way: * I made a table showing what bonds between atoms, and how many of each, were made. Alcohol Bonds Broken Bonds Made C-H C-O O-H O=O C-C O-H C=O Methanol 3 1 1

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

    * Metal Beaker (Copper Can) * Clamp Stand * Heat Proof Mat * Safety Goggles * Digital Weighing Scales * Bunsen Burner/Matches * Thermometer Diagram Results for preliminary Temperature (�C) Mass (g) ALCOHOL BEFORE AFTER BEFORE AFTER Ethanol 29�C 39�C 168.97 168.23 From the results I can gather the following

  1. Finding a material's specific heat capacity

    Accuracy: The power supply can be set to various voltage settings - for this experiment, 12V was chosen. However, due to various factors such as internal resistance, this stated value is often different to the true voltage in the circuit and the voltage across the heater.

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

    From my results and the manufacturer's results I can see there is a big difference this is because the manufacturer uses a calorimeter. The body uses energy to conduct vital functions and maintain itself at a constant temperature. By using a Calorimeter scientists have established the amounts of energy in the body's fuels-carbohydrates, fats, and proteins.

  1. Choosing a light source

    Below is a diagram of a solar yard light. The solar yard lamp consists of the following things:- * A case made from plastic * Solar panel on top made from solar cells * A single AA NiCad battery * A controller board * An LED light source * A

  2. Investigation to see the relationship between actual and theoretical energy released when burning different ...

    We will be using Propan-2-ol, Butan-1-ol and Pentan-1-ol, it will be interesting to see if they make a difference to the results as they have different physical properties although the chemistry of all the isomers of each molecule is the same.

  1. Investigating The Heat Of Combustion Of Alcohols.

    we see that the total energy produced from the combustion of methanol is 589.5kJ. This energy is used to heat up the water in the copper calorimeter. Some energy will also be used to heat up the copper calorimeter. For example with ethanol the equation would be: ethanol + oxygen carbon dioxide + water + energy CH3CH2OH + 3O2 (g)

  2. Resistance of Carbon Putty.

    This graph also appears to reach a point on the graph where it levels off when I draw in my line of best fit. This point is reached at 12 cm in length. My prediction that the resistance would double as the length of the putty doubled was nearly correct.

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