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

Comparing the Enthalpy Changes of Combustion of Different Alcohols.

Extracts from this document...

Introduction

Michael Taylor Comparing the Enthalpy Changes of Combustion of Different Alcohols: Planning Assessment The enthalpy change of combustion of a fuel is a measure of the energy transferred when a mole of the chosen fuel burns completely. The value for the enthalpy change in a fuel can be found by using the burning fuel to heat water and using the fact that 4.2J of energy are required to heat 1g of water by 1oC. In this activity I am going to find the enthalpy change of combustion for 5 alcohols: Methanol (CH3OH), Ethanol (C2H5OH), Propan-1-ol (C3H7OH), Propan-2-ol (C3H7OH) and Butan-1-ol (C4H9OH). I am doing this to investigate how molecular structure of a molecule affects its enthalpy change. Equipment List: - Spirit Burners containing: Methanol Ethanol Propan-1-ol Propan-2-ol Butan-1-ol - Small Copper Can or other metal container to act as a calorimeter - 0-110oC Thermometer - 50 cm3 Pipette + Pipette filler - Access to a balance - Bunsen Burner with Splints - Draught Shielding - Clamp Stand - Burn-Proof Matt - Distilled Water Plan: -Put 100 cm3 of water in the calorimeter and record its temperature. (The same temperature each time will produce the most accurate results.) ...read more.

Middle

are harmful. -The results will be more accurate if a lid on the burner is used, as it reduces evaporation of the alcohol. I have chosen the named alcohols, as they are all straight chain alcohols progressively gaining a carbon atom from 1 - 4. This will allow for easy comparison of the alcohols. I chose Propan-2-ol to compare structural isomers to other structural isomers. Results Tables: Analysing Evidence: [C=12, H=1, O=16] Methanol (CH3OH): 100 x 4.2 x 14.83 = 6.22 kj per 1.19g of fuel 6.22 = 5.22 kj/g 1.19 Molar Mass: 12 + (3x1) + 16 + 1 = 32 1 mol of Methanol = 32g 5.22 x 32 = 167.04 kj Enthalpy Change of Combustion for Methanol = 167.04 kj Ethanol (C2H5OH): 100 x 4.2 x 14.33 = 6.01 kj per 0.47g of fuel 6.01 = 12.78 kj/g 0.47 Molar Mass: (2x12) + (5x1) + 16 + 1 = 46 1 mol of Ethanol = 46g 12.78 x 46 = 587.88 kj Enthalpy Change of Combustion for Ethanol = 587.88 kj Propan-1-ol (C3H7OH): 100 x 4.2 x 14.83 = 6.23kj per 0.41g of fuel 6.23 = 15.20 kj/g 0.41 Molar Mass: (3x12) ...read more.

Conclusion

This means the Balance has quite a high amount of percentage error. There are other sources of error, such as the positioning of the calorimeter, use of a different batch of distilled water half way through the experiment, and doing the experiment over two days. Overall, however, the experiments results are fairly reliable. They have been made so by doing repeats of the experiment and calculating an average. The more repeats done, the more accurate the results, but time allowed for 3 repeats per alcohol. If I was to do this experiment again, I would more than likely use a longer time period to do it in, rather than spreading out the experiment over 2 days. I would also do more repeats per alcohol, possibly 5 repeats per alcohol. Another way to make the experiment better would be to do it in a small room. You would have to make sure the room however was well ventilated as many of the alcohols are dangerous to inhale. A better draft shield would be helpful, as well as putting the calorimeter closer to the flame. It would make the experiment a lot quicker if a 100 cm3 pipette was supplied, rather than the 50 cm3 pipette, which was supplied, as the majority of the time to do the experiment was taken up by filling the pipette to refill the water in the calorimeter. ...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)

    The thermometer bulb was touching the bottom of the tin can, which may have inadvertently gained extra degrees on its reading, not giving the real temperature of the water. This may give rise to parts of the water is at a different temperature to the rest, altering my degree of accuracy at which I read off the thermometer.

  2. Investigating the Combustion of Alcohols

    Fit the lid with the thermometer in place. 5. Take a small spirit burner that is almost full of methanol and place it on the balance to weigh to � 0.01g. Weigh each of the alcohols being used. Butan-1-ol is the only exception because it is not available in the school laboratory.

  1. Comparing the Enthalpy changes of Combustion of different Alcohols.

    x (temperature rise in water) x 4.2J 194.3g x 21oC x 4.2J = 17137.26J (2.d.p.) * Molecular Formula: CH3CH2CH2OH * Structural Formula: H H H H C C C O H H H H * Mass of 1 mole of fuel: (C:12; O:16; H:1)

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

    As I am using data books for the enthalpy change of combustion it will be an insufficient use of my time to calculate the value using this method for all of the alcohols that I plan to use. Data obtained from Data sheets from Salters Advanced chemistry 2000, Table 20

  1. Investigate the enthalpy change of different alcohol

    Average (minute'second") 1cm 0'31"57 0'31"47 0'31"52 2cm 0'28"25 0'24"97 0'26'61" You can see that as wick length increases, time for the temperature in distill water to reach 30C decrease. I guessed that as the wick length increases, more fuel is being burnt, so more energy is ready to heat up the water particles in the can.

  2. "Could Sainsbury's add value to their business by using an alternative fuel for their ...

    is currently being implemented by Cadbury's * There are about 1,000 LPG refuelling sites across the UK. * LPG vehicles drive like a petrol vehicle * Fixed power shift grants towards the cost of buying a new LPG vehicle or converting an existing one to run on LPG.

  1. Molar Heat of Combustion of Alcohols

    � this gives us the energy absorbed by the container when one 1g of alcohol was burnt. 1365/0.42=3250J One mole of butanol weighs 74g so we times the energy used by 1g by 74. This will therefore give us the energy absorbed by the water when one mole of alcohol is burnt.

  2. To compare the efficiency of different alcohols as fuel sources

    I also predict that butanol will have the largest temperature change as it burns quicker and will heat the water up more within the 2 minutes. On the whole I believe that at this stage, theoretically butanol will turn out to be the most efficient.

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