Energy Released From the Complete Combustion of Different Alcohols

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Name        : Youhanna Andraws Kamal El Alfy            

Class        :        4/6

Activity        :        C5.01-05

Dated        :        10-3-2004



Energy Released From the Complete Combustion of Different Alcohols

Energy Released From the Complete Combustion of Different Alcohols


1-The Aim of work:

A fuel is a substance which can be conveniently used as a cheap source of energy. In this experiment the key factor that I plan to investigate is the amount of energy released from burning different fuels. I will be burning five different alcohols, ethanol, methanol, propanol, pentanol and butanol. My aim is to find the energy produced from burning of each one of these alcohols and afterwards calculate the heat value for each. This energy is given out when forming bonds between the new water and the carbon dioxide molecules I have used water since it is safe, abundant and has a specific heat capacity which is 4.18. In a chemical reaction bonds between atoms in the reactant molecules are broken and new bonds are formed in the products. 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.

  2- Equations:

        CH3OH        +        2 O2        CO2        +        2 H2O        Methanol

        C2H5OH        +        3 O2        2 CO2        +        3 H2O        Ethanol

        2 C3H7OH        +        9 O2        6 CO2        +        8 H2O        Propanol

        C4H9OH        +        6 O2        4 CO2        +        5 H2O        Butanol

        2 C5H11OH        +        17 O2        10 CO2        +        12 H2O        Pentanol

3- The Tools That I Used Are:

  • 5 spirit burners; each one containing one of the five alcohols ethanol, methanol, propanol, pentanol and butanol.
  • A empty can of any fizzy dink, but it should have thin walls.
  • Thermometer.
  • Accurate electronic balance.
  • Matches.
  • Measuring cylinder for make accurate volume of water (volume of water = 200 cm3).

4- The used apparatus:

5- Procedure: 

  1. Wash the can, dry it by tissue paper, measure it by the electronic balance and record the reading.
  2. Measure 200 cm3 water by the measuring cylinder, pour it into the can, measure it by the balance and record the reading. By this step you can get the water mass by subtracting the can mass from the mass of the water plus the can.
  3. Measure the mass of the spirit burner before burning.
  4. Put the thermometer in the can for a minute to get the water temperature and record this as the initial temperature.
  5.   Put the metal can on the spirit burner, make the spirit catch fire by matches and put the thermometer inside the can.
  6. Heat the can until the thermometer reading reaches 75°C. By this step you can get the rise in temperature by subtracting the initial temperature from the final temperature.
  7. Measure the mass of the spirit burner after burning and record it. By this step you can get the mass of fuel consumed by subtracting the final reading of the spirit burner from the initial reading of the spirit burner.
  8. The calculation of the ΔH value of the fuel can be given from the following formula:

                 Energy Given Out by Fuel        =        Energy Absorbed by Water

        Moles        x        ΔH        =        M        x        C        x        ΔΘ

                X        ΔH        =        M        x        4.18        x        (t2-t1)

Where        “ΔH”        is the heat value of the used fuel        =        (kJ/mol)

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        “C”        is the specific heat of water        =        4.2        J/g K

        “M”        is the mass of water        =        (kg)

        “m1”        is the initial mass of burner        =        (g)

        “m2”        is the final mass of burner        =        (g)

        “t1”        is the initial temperature of water        =        (°C)

        “t2”        is the final temperature of water        =        (°C)

  1. Apply the above steps for the other four fuels and record your results in a table form.

  1. For fair test:

  In order to achieve a fair test, these experiments should be carried out using the same following conditions:

  •   Same apparatus.
  •  Same volume of water (200 cm3, using a measuring cylinder).
  •  Same initial temperature (room temperature).
  • ...

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