RECRYSTALLIZATION OF BENZENE

Purpose

The main purpose of my laboratory experience is to purify benzene acid to a solid.

Procedure

• With a spatula, weigh 1.50g of benzene and place it on a weight paper
• Put benzene in a eureka flask
• Using a graduated cylinder, measure 20ml of distilled water
• Put a hot plate in a vent and turn heat to 6⁰ Place eureka flask on plate and pull door down so that you cannot inhale the fumes.
• Let the flask remain on the hop plate until it dissolves
• After benzene has dissolved, turn the hot plate off and remove the flask
• Place the hot flask in a vent and let it cool down and then observe what it looks like
• Using a spatula, poor benzene in a suction filtration
• When it’s done filtering, poor it in a watching glass and let it sit there for 2 days
• Add crystal to the melting point tube and ensure that the crystals are at the bottom of the melting tube
• Place and leave it in the melting tube until it reaches its melting point

Data

The starting time for the experiment was 11.10a.m

At 11.16a.m crystals started to form

The melting point of the crystals started to approach 115⁰ C and finally at 199⁰ C

Basically the experiment took 3 minutes melting the ice

Drawing

                                                O

                                                H                     O

 

 

 

 

(Steven et al., 2016)

Discussion and conclusion

The re-crystallization of benzene does not dissolve at low temperature. It does at high temperature and separates water of crystallization using suction filtration. Pure re-crystallized benzene has a shinny appearance or a white crystal powder.  The melting point of benzene during the experiment was 119⁰ C. Since the melting point of impure benzene ranges from 118⁰ C-120⁰ C; it means that the M.P of benzene during the experiment was of an impure substance. The melting point of pure benzene is 248⁰ C (William, 2006). Its high melting point is mainly caused by the stronger intermolecular forces of benzene.

Considering the structure of benzene, benzene has a double hydrogen bond between oxygen. Moreover, because of the carbon-carbon bond, it makes it to have a planar structure.  It is the simplest hydrocarbon compound (Steven et al., 2016).

 

References

Steven, S. Z, Susan A. Z, & Donald J. D. (2016). Chemistry. Cengage Learning Press

William, A.M. (2006). Organic chemistry: Volume 3 of Elements of Chemistry: Theoretical and Practical, Elements of Chemistry: Theoretical and Practical. J. W. Parker and son