AP Chemistry: Formation of Esters WW Frey Scientific $ WW Frey Scientific $47.95

Overview  AP Chem is a year 2 Chem class!! Organic lab possibilities?  For AP Chemistry class (Demo/Combination of labs?)  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  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.  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: CH 3 COOH + CH 3 OH -> CH 3 COOCH 3 + H 2 O  Concentrated Sulfuric Acid will: 1.Act as a Catalyst (make the carbonyl group more electrophilic) 2.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!!  Example Reaction: CH 3 COOH + CH 3 OH -> CH 3 COOCH 3 + H 2 O  Concentrated Sulfuric Acid will: 1.Act as a Catalyst (make the carbonyl group more electrophilic) 2.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.)  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 1.Break into 8 (EIGHT) groups [1 sample/gp] -- Group # = Sample # 2.Follow procedure steps 3-7 ONLY! 3. 4.Waft. Write scent description. 5.Rotate to all groups - waft & write scent description. ARE THEY DIFFERENTIABLE?! 1.Break into 8 (EIGHT) groups [1 sample/gp] -- Group # = Sample # 2.Follow procedure steps 3-7 ONLY! 3. 4.Waft. Write scent description. 5.Rotate to all groups - waft & write scent description. ARE THEY DIFFERENTIABLE?!

Concluding Thoughts 1.Lab procedure and analysis is pretty light for AP Chemistry. (It takes more than C to make a lab worthy of AP Chemistry.) 2.Students synthesizing all samples is a waste of time. 3.Could be modified/added to to bulk up the difficulty & analysis. Unknown samples? End of year lab? 1.Lab procedure and analysis is pretty light for AP Chemistry. (It takes more than C to make a lab worthy of AP Chemistry.) 2.Students synthesizing all samples is a waste of time. 3.Could be modified/added to to bulk up the difficulty & analysis. Unknown samples? End of year lab?

Suggestions? Ideas? Modifications?

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