ring clamp thermometer
metal beaker
100ml water
retort stand
Burner
Observations were made upon the experiment. The base of the metal beaker was covered with soot (carbon) after burning each type of alcohol. However, more soot appeared when burning butanol. A strong aroma was also released by methanol, ethanol and butanol, although methane released the strongest smell. Also, the four alcohols burnt with different flames. Some were brighter (butanol), lighter (methanol), larger (propanol), smaller and dimmer (ethanol).
The four alcohols were weighed before and after the experiment. The table shows the amount of fuel used:
The amount of heat supplied by the different alcohols can be compared by using the equation to calculate the temperature rise for a standard number of molecules:
temperature rise (oC) =
Number of g of alcohol
Butanol produced the most heat while methanol produced the least. Also, butanol is the most efficient fuel out of the four since it used up the least fuel to heat water by 30oC.
In conclusion, the more atoms the molecules have, the more heat produced. Therefore, large molecules do produce more heat.
As many variables as possible were controlled. The variables we changed were the types of fuels tested. The dependent variables were the amount of fuel used and the temperature. Other factors which could’ve affected the result were taken into account, such as, closing the surrounding windows to keep out the wind.
Our first attempt at this experiment failed because the distance between the base of the tin beaker and the flame were too far apart for any effective result. The experiment only worked after making alterations to the set up of the equipment (moving the beaker closer to the flame from 12cm to 3cm).
Although this experiment was a success in that it we proved our hypothesis correctly and delivered the expected result, there would still be things we could improve. If I performed this experiment again, we would measure the distance between the base of the tin beaker and the flame more accurately, since we forgot that different burners have differing wick lengths and therefore, the height of the flame would differ also. Minor errors in our results owed to that factor.
Safety precautions were taken into account. All of the used alcohols were slightly toxic if ingested or inhaled, highly flammable and caused some form of irritation following prolonged exposure. Among them, methanol was the most toxic. It is recommended to use eye and skin protection during exposure to these alcohols.
A fuel is a store of chemical energy. Some of the properties ‘perfect’ fuels have are being replaceable, easily combustible, safe to store, leaves little waste and does not cause pollution. Methanol (CH3OH), used as a fuel or disinfectant in surgical operations, is a smog-forming, toxic air pollutant that has a negative environmental impact as it contributes to CO emissions. Ethanol (C2H5OH), mainly used in burners to measure heats of combustion, is a smog-forming, air toxin but offers significant greenhouse gas benefits. Propanol (C3H7OH), used in the polymer industry and as a rocket propellant, has no significant negative environmental impact as we are readily exposed to it. Butanol (C4H9OH), used as a solvent, is biodegradable and won’t cause any major environmental impacts.
