Determination of the Solid-Liquid Phase Diagram for Napthalene-Biphenyl Using Thermal Analysis

2077 Words Feb 27th, 2014 9 Pages
Experiment #1: Determination of the Solid-Liquid Phase Diagram for Napthalene-Biphenyl Using Thermal Analysis

Objective

To apply thermal analysis to the two-component system, naphthalene-biphenyl at atmospheric temperature. The analysis will be represented by a solid-liquid phase diagram (freezing point diagram).

Theoretical Principles
Phase Equilibria and the Gibbs Phase Rule

This experiment is conducted in order to study a condensed system (solid-liquid) at constant temperature (atmospheric temperature). It should be noted that the atmospheric pressure is unlikely to be the equilibrium pressure for the system. However, equilibria in condensed systems are not very sensitive to pressure.

The freezing point is determined at
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The supercooling took place for approximately 1 minute. With that in mind, the approximate freezing point is 38.8oC.
In comparison to the pre-lab data,

Errors

Although somewhat negligible, the weight of biphenyl fluctuated between 18.00g and 18.06g when being measured by the balanced.
Further possible errors could have been caused by the mishandling of the initial substances when being transferred to the test tubes. This would have lead to a lesser amount of naphthalene in mixtures 1, 3, and 4 as well as a lesser amount of biphenyl in mixtures 5, 7, and 8.
As well, during the experiment, a small amount of the mixture would accumulate on the stirrer. Furthermore in regards to the stirrer, it did not reach the bottom of the test tube so it could be a possibility that the bottom of the mixture was not in equilibrium.
The explanation for the supercooling of the final mixture could be fatigue of the person manning the stirrer (in all seriousness).

Conclusions

1.

Recommendations

In order to prevent supercooling, an automated stirrer should be implemented rather than a manual one. The currently implemented stirrer requires a consistent and exhausting motion considering the potential amount of time the experiment may take.
In order to prevent

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