1. Davey Hines Jr
INTRODUCTION
Melting point is defined as a range of temperatures that will cause a solid to change states
into a liquid. Melting point is a pivotal physical characteristic of elements, compounds, and
molecules. Having knowledge of the melting point of a substance has many practical
applications, like iron forging. This lab report will detail the materials and methodology used to
conduct this experiment, the results and observations obtained during the experiment, a section
discussing the results and observations obtained, and a concluding section, summing up the lab
in its entirety.
MATERIALS & METHODOLOGY
Organic Compound Melting Point (◦C)
Diphenylamine 53
m-dinitrobenzene 90
Benzoic acid 122
Salicyclic acid 159
Succinic acid 189
3,5-dinitrobenzoic acid 205
Cinnamic acid 133
Urea 271
Table 1: Literature Melting Points

2. Figure 1: Temperature Calibration curve
In exercise C-1, the thermometer was calibrated. To calibrate the thermometer, my group
members and I each determined the melting point of a pure solid provided by the TA. The pure
solids used were diphenylamine, m-dinitrobenzene, benzoic acid, salicyclic acid, succinic acid,
and 3,5-dinitrobenzoic acid. Approximately a milligram of each of these solids was packed into a
capillary tube, then heated in a melting point apparatus fixed with a thermometer to determine
the melting point. The value obtained from this method was subtracted from the literature
melting point to obtain a correction factor (see results & observations section). The capillary
tubes where then discarded.
In exercise C-2, an unknown sample of a pure solid was obtained, and the number of the
sample was recorded in the lab notebook. Two capillary tubes were loaded with the solid. The
first capillary tube containing the unknown solid was heated rapidly to obtain an estimate the
actual melting point. The melting point apparatus was turned off and allowed to cool 10◦C below
the observed melting point. After the apparatus cooled, the second capillary tube was placed in
the melting point apparatus and was heated at a rate of approximately 1-2◦C per minute. After
y = -1.0314x + 5.56
-4
-2
0
2
4
6
8
10
48-51 80-82 119-122 154.5-155.4 189.8-190.9 201-205
CorrectiveFactors V. Melting Point Range

3. the melting point range was recorded, it was compared to the list of unknowns in Table 1C-1 in
the lab manual (see results & observations section). The capillary tubes where then disposed.
For the final exercise C-3, two vials, one unknown and one of cinnamic acid, were
obtained from the TA. The number of the unknown was recorded in the lab note book. Using a
mortar and pestle, the two vials were crushed and mixed. A spatula was then used to transfer a
sample of the mixture into a capillary tube. The melting point was then recorded and the
unknown was determined to be either urea or cinnamic acid (see results & observation section).
RESULTS & OBSERVATIONS
C.1
As discussed in the previous section, six pure solids where used to calibrate the thermometer.
Refer to Table 1 for the literature melting point values. Below is a table of the measured melting
point ranges and the correction factors for the six pure solids used during this portion of the lab.
Organic Compound Melting Point Range (◦C) Correction Factors
Diphenylamine 48-51 2
m-dinitrobenzene 80-82 8
Benzoic acid 119-122 0
Salicyclic acid 154.5-155.4 3.6
Succinic acid 189.8-190.9 -1.9
3,5-dinitrobenzoic acid 201-205 0
Table 2 Observed Melting Point Ranges and Correction Factors. The values with decimals were
obtained with a digital melting point apparatus. Those without a decimal were recorded with an
old fashioned heating apparatus.

4. The formula used to calculate the correction factor is as follows: Literature melting point
value – highest temperature in observed range = correction factor.
Diphenylamine: 53-51=2.
Diphenylamine’s correction factor was relatively low. The low temperature at which
Diphenylamine melts made it time consuming to work with, because the melting point apparatus
was easily overheated and much time was consumed waiting for it to cool off to a temperature
that would allow for calibration using this pure solid.
m-Dinitrobenzene: 90-82=8
This pure solid yielded the highest correction factor. This could be due to the fact that the solid
was heated too quickly, causing a lag in the thermometer’s reading, leading to a melting point
that was too low. If more time was allowed to let m-dinitrobenzene heat, a more accurate melting
point range would have been attained.
Benzoic acid: 122-122=0
A correction factor of 0 for benzoic acid shows a well-executed calibration.
Salicyclic acid: 159-156.4=3.6
The correction factor for this pure solid was the second highest among them all, most likely due
to a lack of attention when the Salicyclic acid was completely melted and the true melting point
was reached.
Succinic acid: 189-190.9=-1.9
Succinic acid had a small correction factor. The discrepancy between the literature value for the
melting point and the melting point observed could be attributed the the imperfect human eye,

5. and attempting to record a value while simultaneously determining if the solid was completely
melted.
3,5-dinitrobenzoic acid: 205-205=0.
The correction factor for this compound was also 0. The calibration for this pure solid was also
highly successful and very accurate.
C.2
During this portion of the experiment, an unknown solid (#3) was determined using the
observed melting point range in comparison to literature values of know pure solid melting point.
The observed melting point for the first capillary tube which was heated quickly was 141-155◦C.
The second capillary tube, which was heated at a rate more slowly and therefore more precisely,
had a melting point range of 134.5-147.5◦C. A more specific melting point range was determined
to be 141-147.5◦C.
C.3
Solid Melting Point Range (◦C)
Cinnamic Acid 133
Mixure of cinnamic acid and vial 2 84-117
As stated in the previous section of this lab report, a mixture of cinnamic acid and an
unknown pure solid was mixed and the melting point range was determined for the mixture.
Cinnamic acid was a yellow, powdered substance, while the unknown vial 2 was spherical in
shape, and white.

6. DISCUSSION AND CONCLUSION
In exercise C.2 of this experiment, it was determined that 2-nitrobenzoic acid was the
pure solid for unknown vial #3. This conclusion was based on the fact that 2-nitrobenzoic acid
has a literature melting point value of the 146◦C, which falls within the melting point range
observed while conducting this portion of the experiment. The discrepancy between the first
melting point range acquired from the first capillary tube loaded with unknown vial #3 and the
second melting point obtained with the second capillary tube packed with unknown vial #3 could
have occurred because one pair of students determined the first melting point range obtained on
an old-fashioned melting point apparatus, while the second pair of students determined the
second melting point range on a digital melting point apparatus.
In exercise C.3, the unknown solid #2 was determined to be urea. Even before the
experiment was conducted, however, it was obvious that the unknown solid was urea because of
the difference in physical characteristics between the unknown vial and cinnamic acid. As stated
in the previous section, cinnamic acid resembled a yellow powder, while the unknown vial was
white and spherical. Logic would tell me that in the unknown vial was also cinnamic acid, it
would look identical to the vial label as cinnamic acid. After mixing the solids and noting the
drop in melting point range, my assumption was confirmed that the unknown vial had to be urea.
The melting value obtained, 84-117◦C, was probably a result of one of these reasons or a
combination of the two: either sweating was confused with melting, or the substance was heated
too slowly. Even considering these potential errors, the mixture melted at a value much lower
than the 133◦C literature value for cinnamic acid.
In conclusion during this lab, I learned that melting point is a key characteristic of a
compound, and determining a melting point for a substance is an invaluable skill to have. Also, I

7. learned that calibrating a thermometer is key in correctly determining a substances melting point.
Lastly, I learned how important consistency and preparation is in conducting a successful lab. It
is vastly important to properly prepare for a lab and consistently execute all steps of the lab.