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Using a solid naphthalene as an example,describe how impurities affects the melting point of a substance.

Using a solid naphthalene as an example,describe how impurities affects the melting point of a substance.

Answers

sharon
(i) Put a very small amount of naphthalene in a capillary tube sealed at one end. You can pull
out the capillary tube from heated glass tubing. Use a rubber band to attach the capillary
tube, sealed end down, to a thermometer. Heat a thermometer and capillary tube in a
beaker of water on a tripod. Use the thermometer to stir the water but do not let water
enter the capillary tube. Slowly raise the temperature of the water. Note the temperature
of the naphthalene when it melts. Let it cool and note the temperature when the
naphthalene solidifies Calculate the average of these two values.
(ii) Use a clean test-tube and thermometer to repeat the experiment using stearic acid, mp
69o, or use any other substance, mp < 100oC.
Mix stearic acid with the naphthalene, thus making the naphthalene impure. Look for
changes in the melting point.You notice that Impurities lower the melting point.
sharon kalunda answered the question on April 12, 2019 at 06:45

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