Freezing Point of Naphthalene Essay

604 Words Oct 14th, 1999 3 Pages
Freezing Point of Naphthalene

I. Purpose

To determine the freezing point of a known substance, naphthalene

II. Materials

ringstand gas source test tube test tube clamps thermometer naphthalene Bunsen burner goggles hose stopwatch

III. Procedure

1. Assemble the Bunsen burner, attaching one end of the hose to the burner and the other to a gas source. 2. Assemble the ring stand so that a ring clamp is attached to the stand holding the test tube that will be used in the experiment. 3. Fill the test tube to approximately 1/8 capacity with naphthalene crystals. 4. Place the thermometer in the crystals so that it is surrounded by the naphthalene powder but not touching the sides
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(See following pages)

VI. Calculations

Using 80.1 oC as the theoretical value for the freezing point of naphthalene, we can now determine percent error.

Percent Error = ((Theoretical - Experimental) / Theoretical) x 100 Percent Error = ((80.1 oC - 79.0 oC) / 80.1oC) x 100 Percent Error = 1.4%

VII. Conclusions

In this lab, we heated the known substance naphthalene in a test tube to approximately 100oC and observed its temperature while it cooled to approximately 70oC. Over a time period of 12 minutes and 30 seconds, we recorded the temperature at regular 15 second intervals, and, with this data, constructed a chart showing the general curve. Upon inspection of the graph and our data chart, we found the experimental freezing point of naphthalene to be around 79oC. This results in 1.4% error when compared to the actual value for the freezing point of naphthalene, 80.1oC. Considering the impurities in the consumer grade naphthalene, the interference of outside air on the temperature of the test tube and its contents, and the inaccuracy of 1/10 measurements on a thermometer graduated by whole numbers, the error we accquired in this lab was minimal and

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