Investigate the relationship between temperature and evaporation rate
Evaporation experiment
Investigate the relationship between temperature and evaporation rate
The hypothesis for this experiment that the higher the temperature the faster
the evaporation rate. I assume this prediction based on the background theory of
moving particle. It states that a substance at a particular temperature has a range
of kinetic energies. The higher the temperature, the faster the energetic particles
vibrate and overcome the attractive forces of neighbouring particles, thus escape
from the liquid as a vapour1.
Design:
The independent variable in this experiment is the different type of liquid (boiling
water at 70° and cool water at 28°
The dependent variables in this experiment are the time for the experiment and
the temperature changed
The controlled variable in this experiment is the dryer
Apparatus:
1. Set up the experiment with 75ml of liquid in a beaker, a dryer, a stopwatch and a thermometer
2. Use the thermometer to check the initial temperature of the 75ml liquid
3. Heat the liquid by using the hair-dryer. Dry the liquid for two minutes,
then immediately measure the temperature by using the thermometer.
Record data in table
4. Repeat step 3 for another 2 minutes for another 2 times
5. Repeat steps 1 – 4 for the other liquid
6. Repeat steps 1 – 5 two times (time constraint)
The photo shows I had carried out my experiment. I was able to observe the
change in temperature as time passed too!
Data Collection
“Data shows the relationship between temperature and evaporation rate”
The calculation:
There is no calculation required in this experiment
Test l:
Type
of
liquid
Cool
water
Boiling
water
Initial
temperature
of liquid
(°C)
Temperature
of liquid after being dried
(°C)
± O.l
2
4
6
minutes minutes minutes
28.O
±O.l
3l.O
±O.l
3l.5
±O.l
32.O
7O.O
58.O
53.O
46.O
Test 2:
Type
Initial
of
temperatur
liquid e of liquid
(°C)
± O.l
Cool
28.O
wate
Boiling 7O.O
r
water
Temperature
of liquid after
dried (°C)
2
4
minute minute
s3O.O s32.O
±O.l
±O.l
6l.O
54.5
being
6
minutes
±O.l
32.O
5O.O
The results support my hypothesis which is the higher the temperature, the more
temperature will be lost when heated (dried), results in an overall drop in
temperature in the boiling liquid. As for the cool liquid, the temperature is gained
as heated (this is not stated above at the hypothesis) but has shown a very
contrasting pattern (will be further discussed in the conclusion section).
The below graphs indicate the rate of change during the six minutes for the two
tests for both cool and boiling liquids (water).
Relationship between between temperature (in boiling liquid) and rate of
evaporation as time and boiling effect increases
80
70
Temperature (°C)
60
50
40
30
20
10
0
0
1
2
Test 1
Minutes
3
4
5
6
7
The graph indicates the boiling effect (drying – heating) on boiling liquid. For both
tests, the temperatures for the liquid go down. At the first two minutes, it is
notified that the temperature falls most severely. The explanation is that the
molecules with kinetic energy are able to vibrate quickly and vigorously, as they
hit the surface they evaporate, leaving the cooler (slower) molecules on the
surface. There is a steady and consistent drop in temperature with no anomaly in
both experiments. This reduction in temperature also proves that water absorbs
latent heat from the surrounding when it evaporates causing evaporative
cooling2. This also proves high degree of accuracy.
Relationship between between temperature (in cool
liquid) and rate of evaporation as
time and boiling effect increases
40
Temperature (°C)
35
30
25
20
15
10
5
0
-1
Test 1
Test 2
0
1
2
3
Minutes
4
5
6
7
The graph indicates the boiling effect (drying – heating) on cool liquid. For both
tests, the temperatures for the liquid go up. At the first two minutes, it is notified
that the temperature increases most rapidly and vigorously. The explanation is
opposite to the graph for the boiling liquid. Thermal energy is transferred to cool
liquid which leaves an impact of the exceeded kinetic energy on the particles.
Particles start to vibrate and thus increase in temperature. 6 minutes is a short
time for measurement of evaporation, because the temperature remains below
the boiling point3.
Conclusion:
In conclusion, the results have greatly supported the initial hypothesis about the
relationship between temperature and rate of evaporation. The higher the
temperature, the faster the evaporation rate therefore a drop in temperature.
Temperature is recorded as most severely fall in the first 2 minutes, since that
time high thermal molecules on the surface gain more kinetic energy and are
able to escape and evaporate quickly from liquid surface. They vibrate vigorously.
As learn from theory, temperature is proportional to the average kinetic energy f
the particles, a lower kinetic energy means a lower temperature and this explains
why he temperature of the liquid falls as evaporative cooling4.
As for the opposite result obtained from cool liquid, it suggests that thermal
energy input to place latent heat of vaporization to the cool liquid and its
surrounding, therefore no evaporation took place, instead thermal energy
increased to the boiling point. This explained for an increase of temperature in
the cool liquid.
There is no anomaly found in this experiment. The patterns fit well with the
theoretical background.
Error:
Small errors occur that we have not carefully planned for the experiment and
therefore struggled at the beginning. This waste of time for struggling reduced
the accuracy for the measurement of temperature, especially for boiling water,
vapour could have been lost and the temperature would decrease. I also
rounded up the thermometer reading if the degree was difficult to identify (in
between two numbers or lines). Small mistake of time to stop the watch is also
considered as an error though it is our reaction time and thus hard to make
realistic improvement.
Limitation:
Time constraint is a major factor that prevented me from repeating the
experiment more time. If I were to have more time, I would surely repeat this
experiment to ensure a stronger set of data result evidence.
Realistic Improvement:
It is important that one looks at as many and different aspects of the
experiment as possible. Next time, I shall plan, design carefully for 1-2 hours
and decided on which aspects would most likely to influence the variable
To enhance the range of results, it is important that I should repeat the
experiments many times and average the result.