Things which could affect the speed of evaporation are:
- Type of liquid;
- Colour of liquid;
- Colour of container;
- Aperture of container.
I am going to investigate how the type of liquid affects the speed of evaporation. I will create an experiment in order to find out.
The Experiment
Plan
I will pour 20cm³ of three different substances (ethanol, water and paraffin) into separate beakers. I will then place the three beakers into an incubator at 60°C for 30 minutes. After 30 minutes I will remove the beakers from the incubator and pour out the liquid from each beaker into its own measuring cylinder in order to find out how much of each substance evaporated.
Equipment
I will need:
- Incubator;
- Stopwatch;
- Thermometer;
- 3 measuring cylinders
- 3 beakers;
- Ethanol;
- Paraffin;
- Water.
Prediction
I predict that the water will evaporate the most because it has the lowest atomic mass (18) of the three substances. Paraffin will hardly evaporate, if at all, due to its huge atomic mass (632!).
Results
The data that I have collected may be inaccurate because while the beakers were in the incubator somebody tampered with the temperature control. However, there was not enough time for me to repeat the experiment and recollect all of the data so I am continuing with the data I already have. An improvement to the accuracy of the experiment would be to weigh the beakers of liquid before and after placing them in the incubator as no droplets would be lost transferring liquid between beakers.
Analysis
The results of this experiment show that ethanol evaporated the most with just 10cm³ remaining after being in the incubator for 30 minutes. The water didn’t evaporate as much as I expected with 18cm³ left after 30 minutes. Paraffin did not evaporate at all – after 30 minutes there was still 20cm³ left in the beaker.
These results partly support my prediction and partly contradict it. They support it in that as I predicted, paraffin did not evaporate at all. However, they contradict it in that ethanol evaporated much more than water did. I have no idea why this happened because water had a lower atomic mass than ethanol.
Evaluation
The only part of my results which I expected was that of paraffin not evaporating. The results for ethanol and water surprised me as the substance with the lower atomic mass (water) did not evaporate nearly as much as the substance with the higher atomic mass (ethanol).
The experiment could be improved for greater accuracy by weighing the beakers of liquid before and after they are placed into the pre-heated incubator for a set amount of time. This would prevent loss of water when transferring substances between containers.
To be entirely satisfied with my data I would need to do this experiment at least three times to ensure that I had collected accurate data. I would also ensure that the actual liquid was at 60°C for 30 minutes rather than the environment into which the liquid was placed being at 60°C for 30 minutes.
Alex Powell – Evaporation Coursework - Page of
