Simple Distillation
Experiment 2:
Simple Distillation: Identification of a Petroleum Hydrocarbon
Simple Distillation
Results
The objective of this experiment was to identify a petroleum hydrocarbon from an unknown
sample. The unknown sample received was identified as (#230). The primary test used was to
create a distillation apparatus that rested on a hot plate, in order to measure the unknown
hydrocarbon’s boiling point.
Boiling Point: simple distillation method (OC)
Boiling points were measured at three different temperatures:
1) Starting Boiling point: 29 OC
2) Medium Boiling point: 49 OC
3) Last boiling point: 55 OC
Index of refraction (n)
Index of refraction was used to identify the medium in which light is propagating through.
nt is the measured refractive index 1.4249 at temperature 24.67 OC
n20 is the reported value at 20 OC
n20 = nt + 0.0045(t-20)
= (1.4249) + 0.00045 (24.67 – 20)
= 1.427
Density (D)
D=m/V
At 1mL: D =
0.8381𝑔
At 2mL: D =
At 3mL: D =
1𝑚𝐿
1.6442𝑔
2𝑚𝐿
2.4437𝑔
3𝑚𝐿
Average Density: (
= 0.8381 g/mL
= 0.8221 g/mL
= 0.8145 g/mL
0.8381+0.8221+0.8145
)
3
= 0.8249 g/mL
Boiling Point: Capillary – tube measurement:
Simple Distillation
The boiling point was obtained by inserting a sample filled micro tube, into a melting point
apparatus until bubbles began to form. Two different temperatures were recorded.
Starting boiling point: 61.7 OC
Exiting boiling point: 86 OC
Contrast between unknown sample and known hydrocarbons
Hydrocarbon
BP: distillation
OC
Index of
refraction n20
Density
(g/mL)
BP: Capillary
tube OC
Cyclopentane
Hexane
Cyclohexane
Unknown
49
69
81
55
1.4065
1.3749
1.4266
1.427
0.746
0.659
0.779
0.8249
49
69
81
86
Conclusion:
The objective of this experiment was to deduce what the unknown hydrocarbon was (#230).
After extensive testing of four different methods, it can be concluded that the unknown
hydrocarbon was in fact cyclohexane. Upon comparing and contrasting the experimental data
to other know values, is it evident that the unknown sample parallels that of cyclohexane. Its
index of refraction 1.4266, is identical to the unknown’s index of 1.427. Further comparisons
can be said about cyclohexane’s density; 0.779g/mL and boiling point of 81 OC. The unknown
has a density of 0.8249 g/mL as well as a boiling point of 86 OC which are very similar. It is to be
noted that the boiling points from the simple distillation did not align. There is a remarkable
gap between boiling points of unknown sample (55 OC) and cyclohexane (81 OC). After
additional thought, this could be the by-product of premature stoppage, instead of allowing the
boiling point to continue to rise and obtain its official boiling point.