1. Different Concentrations Affect on Boiling Points
Introduction
This experiment will show how changing the concentration of a substance can effect its
boiling point. This will be tested by mixing different concentrations of ethanol and water
in a mixture to see if it changes the boiling point. The boiling point is when a liquid
reaches the point that it begins to turn into a gas. The boiling point is also the highest
temperature a substance can reach. The boiling point is dependent on the molecular
weight of a substance. So the higher the molecular weight the higher the boiling point.
The accepted value for the boiling point of ethanol is 78 degrees Celsius and water is 100
degrees Celsius. So when these two liquids are mixed at different concentrations the
change in boiling points will be observed. It is expected that when the concentration of
ethanol is higher than the concentration of water the boiling point will be lower than the
accepted boiling point of water and will begin to become closer to the accepted boiling
point of ethanol. When the concentration of water is higher than the concentration of
ethanol the boiling point is expected to be higher than the accepted boiling point of
ethanol and will begin to become closer to the accepted boiling point of water.
Research question:How do the concentrations of CH3CH2OH andH2O affect the
temperature of its boiling point?
Variables
The independent variables are CH3CH2OH and H2O. The dependent variable is the
boiling points of each mixture of CH3CH2OH and H2O. The independent variables will
be changed through mixing different concentrations of each. This will create the
dependent variable, different boiling points caused by the changes in concentrations. The
controlled variables that will affect the dependent variable are the amount of liquid each
trial, the concentrations of the liquids and temperature of scale. Each trail will have the
same amount of liquid in the test tube to ensure that the amount of liquid being boiled
remains constant for each trial. To ensure each test tube has the same amount of liquid a
25 0.5 mL graduated cylinder will be usedto precisely measure the correct amount of
each liquid. It is important that when the concentrations are changed they are also
measured precisely. So this will be ensured the same way the previous will be measured.
The last controlled variable is making sure the water bath is consistently boiling. This
will be done by having the hot plate set at the highest temperature and when the water
bath reaches a constant boil the temperature will be decreased to a lower temperature.

2. Materials and Procedure:
CH3CH2OH (ethanol)
H2O (water)
100 mL test tube
400 mL beaker
25 mL graduated cylinder
Hot plate
Logger pro temperature
probe
Test tube rack
Clamp stand for test tube
Glass beads
Figure 1shows the materials used in the experiment.
First, the hot plate is heated. Then fill a 400 mL beaker more than half way with water
and place on hot plate. Next, fill a 100 mL test tube with 30 mL of pure ethanol. Attach
the test tube to clamp and adjust clamp position so 75% of the
test tube is submergedin the beaker of water. Use logger pro to
find out when the ethanol reaches its boiling point. Connect
temperature probe to logger probe and place probe fully in the
test tube. Add four glass beads to test tube and use glass rod to
stir the liquid in the test tube as it boils. Then repeat this
process for each trail. The nest trail will be 100% water,
however after water the trials will be different concentrations of
water and ethanol. The same boiling procedure will be done but
the measurement of each liquid will be different. First, fill the
100 mL test tube with 50% ethanol and 50 % water. Record
this boiling point for three trials. Then fill the test tube with
40% ethanol and 60% H2O. Record the boiling point of this
mixture. Repeat this mixture for two more trials. Then put 60%
ethanol and 40% H2O. Record this boiling point and then repeat
this mixture for two more trials. Next fill the test tube with 20%
ethanol and 80% H2O. Record this boiling point and repeat for
two more trials. Then fill the test tube with 80% ethanol and
20% H2O. Record this boiling point and repeat for two more
Figure 2 shows the set up of the
trials. After all trials are recorded, calculate the average of the
experiment.
three trials for one concentration by adding the three trial
temperatures and dividing by three.

3. Data Collection and Processing
Table 1 shows boiling points for three trials of each concentration. Average of all three
trials boiling points are shown.
Boiling Point
Ratio of substances Temperature Temperature Temperature Average
( 0.5 ( 0.5 ( 0.5 Temperature
Trial 1 Trial 2 Trial 3 (
Ethanol 80.1 79.8 79.8 79.8 0.2
30 mL
Water 98.5 99.6 98.6 98.9 0.6
30 mL
50% ethanol- 15 mL 83.7 84.1 84.9 84.2 0.6
50% water- 15 mL
40% ethanol- 12 mL 85.6 85.4 85.4 85.5 0.1
60% water- 18 mL
60% ethanol- 18 mL 83.0 83.3 83.2 83.2 0.2
40% water- 12 mL
20% ethanol- 6 mL 90.1 90.5 90.7 90.4 0.3
80% water- 24 mL
80% ethanol- 24 mL 81.1 81.1 81.4 81.2 0.2
20% water- 6 mL
Calculation of average for 50% ethanol and 50 % water:
= average
= 84.2
Uncertainty of average:
= uncertainty
= .6
Average of 50% ethanol and 50% water = 84.2 0.6

4. Time vs. Temperature of Boiling Point
80% ethanol and 20% water
Graph 1 shows the boiling point of 24 mL of ethanol and 6 mL of water mixed. Where
the line begins to stop increasing, shows that the boiling point is near 81.1 .
Time vs. Temperature of Boiling Point
20% ethanol and 80% water
Graph 2 shows the boiling point of 6 mL of ethanol and 24 mL of water mixed. Where
the line begins to stop increasing, shows that the boiling point is close to 90.7 .

5. Table 2- shows the qualitative observation for each trial.
Boiling Point
Ratio of substances Trial 1 Trial 2 Trial 3
Ethanol Water bath and test tube Same as previous trial. Same as previous trials.
30 mL boil at similar times.
Bubbles form when stirred.
Water Takes longer to boil in test Same as previous trial. Same as previous trials.
30 mL tube than water bath. Do not need to stir to
form bubbles.
50% ethanol- 15 mL Water bath boils before Similar observations as At boiling point only big
50% water- 15 mL test tube. first trial. bubbles go to top.
Each time it almost Small bubbles form Bubbles form in water bath
overflows every few around temperature before tube
seconds. probe. can see ethanol not mix
When reach boiling point Bubbles rise from bottom. with water.
no bubbles until move Increase in bubbles as
stick and then explodes. temperature rises.
Once added 4 glass beads
to test tube bubbles were
more constant.
40% ethanol- 12 mL When use rod the bubbles Same as previous trial. Same as previous trials.
60% water- 18 mL happen occasionally. Overflowing most of the
time
60% ethanol- 18 mL water boils before tube. solution overflowed much Same as previous trials.
40% water- 12 mL quicker than other Overflowing most of the
concentrations. time
Overflows more
consistently than other
concentrations 40/ 60
ratios.
20% ethanol- 6 mL Overflowed to the top less Same as previous trial. Same as previous trials.
80% water- 24 mL consistently than 60/ 40
ratio.
Also took longer to
overflow than 60/40.
80% ethanol- 24 mL Overflows a little more At the top most of time At top most of the time and
20% water- 6 mL often than 20/80. and reached very. got there fast.
Also started to overflow
faster than 20/80.

6. Ethanol Concentrations vs. Boiling Point
Graph 3 shows what the boiling points of the mixtures were when there was 20%, 40%,
50%, 60% and 80% ethanol. This graph shows that there is a decrease in temperature of
boiling point when the ethanol concentration is increased.
Water Concentrations vs. Boiling Point
Graph 4 shows what the boiling points of the mixtures were when there was 20%, 40%,
50%, 60% and 80% water. There is an increase in boiling point temperatures when the
concentration of water is increased.

7. Conclusion
This experiment shows that when the concentration of ethanol increases there is a
decrease in boiling points and when the concentration of water is increased there is an
increase in boiling points. When ethanol is 20 % of the mixture the boiling point is 90.4
0.3 and when ethanol is 80% of the mixture the boiling point is 81.2 0.2. This
concludes that when there is more ethanol in the mixture it decreases in temperature to
get closer to the accepted boiling point of ethanol, 78 degrees Celsius. The data also
showed that when 20% of the mixture the boiling point 81.2 0.2 and when water is 80%
of the mixture the boiling point is 90.4 0.3. So this shows that when there is more water
in the mixture the boiling point increases to get closer to the accepted boiling point of
water, 100 degrees Celsius. The percent error in the boiling point of 100% ethanol is
shown below:
–
100 = % error
–
100 = 2.26% error
This percent error is relatively low, showing that the experiment is relatively accurate to
the accepted boiling point of ethanol. However, since the percent error was 2.26% error
this could also have caused minor complications when finding the temperatures of the
boiling points.
The percent error for the boiling point of 100% water is shown below:
–
100 = % error
–
100 = 1.11% error
This is also a low percent error showing that the boiling point of water was close to the
accepted boiling point of water. But 1.11% error could still cause small adjustments in
temperatures when finding the boiling points. Since both percent errors of ethanol and
water boiling points were not exactly the theoretical value, this could mean that there
might some systematic error in the experiment.

8. Evaluation
A systematic error that could be possible in this experiment is that at the
beginning of this experiment when boiling mixtures with a higher concentration of
ethanol, bubbles were unable to form on their own. The only way to have the mixture boil
consistently was to stir the mixture consistently and add four glass beads to the test tube.
So in order to get enough data to find the boiling point of the mixtures, the mixtures had
to be stirredconstantly when they began to reach high temperatures. This is a weakness
because if the stirring stopped the temperature could have increased or decreased to an
incorrect value. This could cause inaccuracy in the boiling point of the mixture. To fix
this problem it would have tobe insured that the stirring never stopped while the mixture
was reaching its boiling point.
The first weakness leads into a random error that some of the mixture would
overflow over the top of the test tube. When there was more ethanol in the mixture, it
seemed to overflow out of the test tube. This could have caused some water or ethanol to
come out of the test tube, which then would alter the concentration of each in the mixture.
This would then have an effect on the temperature of the boiling point either making it
higher or lower than it should have been. A way to improve this weakness would be to
use a larger test tube so that it will not reach the top of the test tube when boiling.
Another systematic error that was in this experimentwas not knowing how pure
the ethanol was. This could have changed the results because the temperature might not
have reached its highest boiling point or it could have been higher than ethanol’s actual
boiling point. The only way to fix this problem would be to ensure it was 100% ethanol.
A limitation to this experiment was the decision to be more efficient with time
and decrease overflow by taking smaller samples than originally planned. Each sample
had 30mL of mixture in the test tube. This is because the mixture would be able to boil
quicker allowing more trials to be conducted for a wider range of data. Also when first
starting the experiment the liquid filled more than half of the test tube, so when the
mixture boiled most of the mixture overflowed out of the test tube. Decreasing the
amount of mixture in the test tube could have caused the temperatures of boiling points to
be a little less than its actual boiling point because it was a relatively small amount of
mixture, allowing it to boil quicker with less overflow. A way to improve this is to use a
larger beaker and test tube to decrease the amount of liquid that was lost from overflow.
Also to be more efficient with time many samples could be taken at one time by having
three hot plates heating three samples at a time. This would allow larger samples to be
boiled in the same amount of time one sample would be boiled.

9. Works Cited
"Boiling Points." HeartMagic- The Music of Gary Stadler. Web. 07 Mar. 2012.
"Ethanol." UCC Home Page.Web. 07 Mar. 2012.