Chemistry lab report

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Recommended: Experiment preparation of organic compounds

The goal of the project was to characterize an "unknown" organic acid in order to make a proper identification of the acid, while learning proper techniques for scientific measurement and analysis of error.

In order to ensure the most accurate data, a purification was performed by the process of recrystallization. To perform the recrystallization the powder was dissolved in a minimal amount of hot ethanol/H2O solvent that allowed the unknown powder to crystallize properly when cooled. This process allowed for the removal of soluble impurities when suction filtered. A sample of the unknown acid was weighed at 8.24 g, and it was found that 164ml of a 40% ethanol, 60% H20 solvent dissolved the 8.24 g of unknown acid when heated. The beaker containing the dissolved acid was then placed in a beaker containing ice, allowing the unknown acid to recrystallized. After vacuum filtration, the recovered unknown was dried and weighed at 6.92 g. The percent recovery was determined by the following calculation: (8.24--6.92)8.24 x 100% = 16% loss = 84% recovery of unknown.

The melting point of the unknown was determined for both pure (recrystallized) and impure (original) powders. To perform thee melting point procedure the powders were placed in small tubule. The tubule was placed in a Mel-temp device and the melting range was recorded. The data is present in the form of a range in the following chart:

"Melting Point"

Substance Starting point (°c) Ending Point (°c)

Pure Acid (recrystallized)

Pure Acid 2nd Range 125.3

7 129.2

6

Impure Acid (original) 124.1 128.2

In order in determine the equivalent weight of the unknown acid, a base was needed at a known or "stan...

... middle of paper ...

...erivative of the unknown acid, it was determined that the unknown acid 94 is sebacic acid [HOOC(CH2)8COOH] whose structure is shown below.

A comparison of the experimental value for the melting point of the melting point of sebacic acid yields an error of 5%, represented by the following calculation: (133°C-125°C)/133°C x 100% = 5%. A comparison of the experimental value for the equivalent weight of sebacic acid yields an error of 2.5%, determined by the following calculation: (101-98)/101x100% = 2.5%. A comparison of the experimental value for the melting point of the amide derivative of sebacic acid yields an error of 0%. This was determined by the following calculation (168-168)/168x100%=0. On average, the error inherent to the total project was 2.5%. In the future, it would be desirable to further support the identification of the unknown

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