Accuracy
- Use a Wind shield to prevent draught in the lab from affecting the results.
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Use a measure cylinder to measure exactly 20 cm3 of water.
Method
I would suspend a small beaker containing 20 cm3 of water above the alcohol and then I will ignite the alcohol.
I will use a stopwatch to measure the temperature of water every 30 second and how long it would take to boil.
- The Independent variable-the variable that can be changed, in this experiment is the alcohol.
- The Dependent variable- the variable that can’t be changed, the amount of water.
- The control variable-the variable that is kept the same, the distance of flame from beaker containing water and the temperature
Results
Conclusion
According to my results Propanol gives the most heat output as it boils the water in just 2.55 minutes.
Ethanol boils the water in 3.59 minutes and Methanol boils the water in 4.25 minutes, Methanol is more than 1.5 slower than Propanol.
METHANOL
ETHANOL
PROPANOL
As the number of carbon and hydrogen increase in the alcohol, the faster it could boil the water.
My prediction was right as I predict that Propanol would give the most heat output, because it has more carbon and hydrogen than other two alcohols.
This graph shows how much alcohol was burned to boil the water.
1 gram of Methanol was burned in 4.25 minutes to boil the water. It takes too much time, but it is economy.
2 grams of Ethanol were burned in 3.59 minutes to boil the water.
4 grams of Propanol were burned in 2.55 minutes to boil the water I think this is the best fuel because it boils the water in minimum amount time.
This graph shows how much alcohol burns per minute.
Ethanol burns at 0.78 gram per minute, Methanol burns at 0.23 gram per minute and Propanol burns at 1.11 grams per minute.
Propanol burns at a faster rate.
Evaluation
I think my experiment was fair because I used a measure cylinder to measure exactly 20 cm3 of water and there were no spillage of water so the beakers contained exactly 20 cm³ of water.
I also stopped the time on 100 ºc.
I didn’t have any anomalous result and all the results were reasonably accurate.
I can make the experiment more accurate by measuring the water by pipette and repeating the experiment three times for each alcohol to get an average result.
We can’t get an accurate result for how long it would take the alcohol to boil the water because some of the heat from alcohol merges into open air. If we carry the experiment in close area such as inside an oven the water would boil much quicker.
