Laboratory Activity 2.1.2: Determining the melting point of naphthalene |
Material: » Naphthalene » Water |
Apparatus: » Boiling tube » Retort stand and clamp » Tripod stand » Wire gauze » Thermometer(0 – 110 ºC) » 250 ml conical flask » Stop watch » Bunsen burner » Test tube holder |
Procedures:
► | The animation below shows the procedures of the heating and cooling of the naphthalene. | |||||||||||||
► | (A) Heating of naphthalene
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► | (B) Cooling of naphthalene
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► | (A) Heating of naphthalene
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► | (B) Cooling of naphthalene
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► | A graph of temperature against time is plotted for the heating of naphthalene.
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► | A graph of temperature against time is plotted for the cooling of naphthalene.
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► | In the heating of naphthalene, a water bath is used instead of direct heating.
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► | In the cooling of naphthalene, the boiling tube containing the liquid naphthalene is cooled inside a conical flask.
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► | Stirring the naphthalene continuously also ensures even heating or cooling. | |||
► | A water bath is suitable in this experiment because the melting point of naphthalene is below 100 ºC. | |||
► | If the melting point of the substances is above 100 ºC, the water bath will have to be replaced by an oil bath. | |||
► | Besides naphthalene, the other substance that is suitable for heating by the water bath is acetamide. |
Conclusion:
► | The melting point and the freezing point of naphthalene is 80 ºC |
⇲ For exercise(objective and subjective), download for free on Android OS. | ||
Tq
ReplyDeleteTq
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ReplyDeletewhy is paraffin oil preferred to water in this experiment
ReplyDeleteParaffin oil has a higher boiling point than water (above 100°C). Therefore, it would not evaporate by the time the temperature of both napthalene and paraffin oil reaches above 100°C
DeleteCan i know what are the precautional steps can be taken?
ReplyDeleteheating process
Deletestir the naphthalene to ensure even heating
cooling process
stir the naphthalene to prevent supercooling
Why need water bath
ReplyDeleteA water bath is laboratory equipment made from a container filled with heated water.it is used to incubate samples in water at a constant temperature over a long period of time
ReplyDeleteWhy is naphthalene not heated directly using the Bunsen burner?????????
ReplyDeleteIt is highly flammable
DeleteWhat are some of the assumptions in the experiment
ReplyDeleteWhat is the trend for the heating and the cooling of the naphthalene
ReplyDeleteDuring heating, why does the water bath level higher than the naphthalene??
ReplyDeleteWhys naphthalene stirred continuously during cooling process
ReplyDelete