Esters-Perfume or Food Additive Which?
Ashley, Kamran, and Alex were working as a 7th grade collaborative team conducting a chemistry experiment. Their teacher, Mr. Gonzalez, as part of a unit about chemical reactions were having the class mix an organic acid called butyric and methyl alcohol. The reaction of the acid and the alcohol produced a compound called an ester. To get the chemicals to react they had to be heated in a hot water bath.
While the substances were heating Ashley noticed that a sweet smelling aroma was being produced, characteristic of pineapples. She told Alex who immediately yelled out to the entire class that they had made pineapple perfume! Kamran said that the smell reminded him of a brand of cologne his dad used. Ashley interrupted both partners and stated that she didn't think perfume or cologne was made from esters!
By now several students from other groups had gathered around their workstation. Becky and Gustavo from another collaborative team, both took a smell of the ester. Becky then stated that it did smell like pineapple, but “that this stuff must be an artificial ingredient that companies put in food when they want the food to taste like pineapple, and not a perfume or cologne!” A lively discussion developed.
At this point the story gets more complicated, because three other teams said that their esters didn't smell like pineapples. Mr. Gonzalez requested that one member from each team write the procedure they had used on the chalkboard. This way the entire class could see if every team had followed the same procedure. The class knew that science protocol stated that for a procedure to be valid it had to be reproducible. The class period came to an end before the issue of whether an ester is used, as a cologne, perfume, or food flavoring additive could be resolved.
Your assignment is to follow the directions given by the 7th graders to produce an ester to see if you can reproduce their results, and resolve the issue of perfume/cologne vs. food flavoring additive. Use the online Cyberlab worksheet prepared for this activity. Make sure that you ware safety glasses and follow all laboratory safety rules.
1) To learn more about what esters are used for visit the following ester manufactory's web site.
2) Use the MAD-Scientist Network's search engine and/or visit Our Little Place company's web site to read about how perfumes and/or colognes are made.
3) For definitions of the words perfume, cologne, and esters with suggestions of books to read about each topic go to the Britannica Encyclopedia online.
4) For a discussion about the sense of smell visit the How Stuff website.
When you have finished conducting
this activity send a brief email summary of your results to the other participating
science classes. Hopefully they will be able to reproduce your results.
To send an email click on the "Post Results" icon. (NOTE: when
posting results over the Internet do not write your last name! - safety