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AP Chemistry: Formation of Esters. 530763WW Frey Scientific $47.95. Overview. AP Chem is a year 2 Chem class!! Organic lab possibilities? For AP Chemistry class (Demo/Combination of labs?). Organic Review (1). Acetic Acid Butyric Acid. Organic Review (2).
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AP Chemistry: Formation of Esters 530763WW Frey Scientific $47.95
Overview • AP Chem is a year 2 Chem class!! Organic lab possibilities? • For AP Chemistry class (Demo/Combination of labs?)
Organic Review (1) • Acetic Acid • Butyric Acid
Organic Review (2) • These acids will react with different alcohols [methyl (1), ethyl (2), butyl (4) & octyl (8)], forming ESTERS (and water). • ESTER: • Esters tend to have sweet, fruity smells, which we will detect in the lab today.
Organic Review (3) • Example Reaction: CH3COOH + CH3OH -> CH3COOCH3 + H2O • Concentrated Sulfuric Acid will: • Act as a Catalyst (make the carbonyl group more electrophilic) • Dehydrate the reaction (removing water so more ester can be formed -- LeChatelier) • CAUTION! Use gloves, goggles, and safe lab practices - Conc Sulfuric Acid is 18 M!!
What We’ll Discover Today • How well/long do the esters keep? (Can this work as a demo in class? Pre-made samples?) • Are all of the scents differentiable? (For future lab modifications - determining identities of unknowns) • Do we REALLY need to pour samples into water? (Just waft, right?! H2O Drives reaction to break down the ester! On the other hand, unreacted sulfuric acid may be a problem if not diluted 1st.)
Lab Setup • Break into 8 (EIGHT) groups [1 sample/gp] -- Group # = Sample # • Follow procedure steps 3-7 ONLY! • <We’ll do steps 8-9 ONLY if necessary.> • Waft. Write scent description. • Rotate to all groups - waft & write scent description. ARE THEY DIFFERENTIABLE?!
Concluding Thoughts • Lab procedure and analysis is pretty light for AP Chemistry. (It takes more than C to make a lab worthy of AP Chemistry.) • Students synthesizing all samples is a waste of time. • Could be modified/added to to bulk up the difficulty & analysis. Unknown samples? End of year lab?
Ref • http://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Acetic_acid_atoms.svg/800px-Acetic_acid_atoms.svg.png • http://www.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/2/24/Butyric-acid-2D-skeletal.png&imgrefurl=http://commons.wikimedia.org/wiki/File:Butyric-acid-2D-skeletal.png&usg=__ysSaPc_-P1BeP6q54i03joE0qbI=&h=576&w=1100&sz=20&hl=en&start=3&um=1&itbs=1&tbnid=KreQ1sPhh4D_AM:&tbnh=79&tbnw=150&prev=/images%3Fq%3Dbutyric%2Bacid%26um%3D1%26hl%3Den%26client%3Dsafari%26sa%3DN%26rls%3Den%26tbs%3Disch:1 • http://www.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/9/99/Ester-skeletal.png&imgrefurl=http://commons.wikimedia.org/wiki/File:Ester-skeletal.png&usg=__KXMDdMXsC_ghX4Hqvb-B8VI_-D4=&h=744&w=969&sz=11&hl=en&start=3&um=1&itbs=1&tbnid=gmd_CISuVsAuAM:&tbnh=114&tbnw=148&prev=/images%3Fq%3Dester%26um%3D1%26hl%3Den%26client%3Dsafari%26sa%3DN%26rls%3Den%26tbs%3Disch:1