80/20,20/80, or 50/50 will be used and the melting point
Determination of Melting Point for an Unknown Compound
Purpose/Overview:
Determine the identity of an unknown compound using the melting point.
Melting are point is the temperature at which the solid and liquid phases of a compound in equilibrium together at a certain pressure. The melting point of a substance can be used to assess the purity of a compound as well as determine the identity of an unknown compound.
For this experimen!
first
the melting point of a pure reference compound
(phenacetin, tartaric acid, or acetaminophen)
will
be determined. Then the melting
point of
a mixture
20/BO or 50/50
of
either
of
these compounds in
the
following ratios: 80/20,
will
be determined. The reason for the determining the mixture of these compounds is and widen to view how adding an impurity to a pure substance can lower
the
melting
point
range.
After
determining
the
melting
point
mixture, an unknown compound
of
the
will
be given and the objective is to determine the melting point of the unknown. The unknown can either be tartaric acid, phenacetin, acetaminophen or none of the said compounds.
To
Asses
the identity
of the unknown, a mixture of the unknown and the reference compounds in either of the
following ratios:
80/20,20/80, or
50/50
will
be
used
and
the
melting
point determined. If the melting point ranges does not vary when mixed
with
one of the reference compounds, then
it
is likely that the unknown is that particular reference compound.
Melting Points
Purpose/Overview:
The goal of this lab is to identify an unknown from a set of possible compounds by comparing literature melting point data to experimental melting point data. The trnknown could possibly be phenacetin, tartaric acid, acetaminophen, or none of them. Acrude measurement of the unknown
will
be taken by increasing the temperature of the melting point apparatus by about twenty degrees per
"
minute in order to determine an approximate melting point. The crude measurement will be followed by a precise measurement which is found by increasing the temperature of the melting point apparatus by about two degrees per minute. For accuracy, phenacetin, tartaric acid, and/or acetaminophen can be melted alongside the unknown to confirm like melting points.
Should the melting point of the unknown be similar to one of the possible compounds, a mixture of the unknown and the compound will be made to identiff (or not) the unknown. If the mixture is of two different substances, the melting point range will be relatively wide, but the melting point will not change if the mixture contains two parts of the same compound. If the mixture's melting point does not differ from the unknown's then the unknown must be whatever it was mixed with.
Consequently, if the melting point is different, then more mixtures should be made in order to rule out all of the possible compounds.
Melting Point Lab Purpose/Overview Statement
The goal of this experiment is to determine the identity of an unknown crystalline solid based on its melting point in comparison with phenacetin, acetaminophen, and tartaric acid. The unknown could be one of these three solids or none of them. To practice taking melting points and to properly calibrate the melting point apparatus, the melting point of a known sample
of
acetaminophen will be taken and compared to that of a mixture between acetaminophen
and
I
t
\ phenacetin at an approximate ratio. Using this comparison technique, the unknown will be identified using its melting point by itself as well as in correspondence with a mixture between the unknown and its suspected identity. If the mixture of the unknown with its suspected identity has a lower and wider ranging melting point compared to the melting point of the unknown by itself, then it is considered to not have that identity.
