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CELLULOSE

First, 8mL of acetic anhydride, 20 mL of acetic acid, and two drops of sulfuric acid in a 125 mL

Erlenmeyer flask. The solution was mixed for 5 minutes to ensure complete mixing. Then, 0.5g of cut

filter paper was added to the solution. Using a stirring rod, the solution was mixed until the structure of

the filter paper completely broke. The flask was covered with parafilm and was kept until the nextmeeting.

On the next meeting, 500mL of water was placed into a 1L beaker. The straw colored solution was

poured and was stirred vigorously until a precipitate was formed. The solution was filtered was filtered,

and water was removed. Next, the residue was placed in an evaporating dish. It was placed in an oven at

110C for 10 minutes. The product was weighed and percentage yield was calculated. Half of the

product was dissolved in enough amount of acetone to make a thin paste. The paste was placed above

the watch glass. Finally, the paste was allowed to dry and the cellulose acetate film was removed.

EXPT 6

A.

Preparation of Standard Solutions

20 mg of salicylic acid was weighed accurately and was transferred into a 100mL volumetric flask.

The volume was filled with distilled water. (Stock solution) 20mL from stock solution was transferred

to a 50mL volumetric flask and was diluted to volume. It was labeled as Solution A. Another 20mL

from the stock solution to a 100mL volumetric flask and, again, was diluted to volume. It was labeled

as Solution B. Next, 20mL from Solution Awas transferred to a 50mL volumetric flask and was

diluted to volume. It was labeled as Solution C. 20mL from Solution Awas transferred to a 100mL

volumetric flask and was diluted to volume. It was labeled Solution D. 20 mL from Solution Cwas

transferred to a 50mL volumetric flask and was diluted. It was labeled asSolution E.

B.

Preparation of the Standard Absorbance Concentration Curve

Absorbance reading of the prepared standard solutions were determined at 296nm using the UV-vis

spectrophotometer. The absorbance values were plotted against the known Salicylic acid

concentration. Linear regression was used to obtain the best fit line.

C.

Preparation of Sample Solutions

40mg of Aspirin was weighed and transferred into a 500mL volumetric flask. Volume was filled

using distilled water. Enough sample was got and absorbance reading at 296nm was taken. 100mL

of the solution was transferred into 4 separate beakers and was placed in ovens set at 50C.

D.

Preparation of Sample Solutions

Enough samples were gotten at 15,30, 45, 60, 90, and 120 minutes. The absorbance reading for each

sample was taken at 296nm. The concentration of Aspirin remaining was determined based on the

standard absorbance-concentration curve. Log C of the Aspirin vs. the remaining time was plotted.

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Then, the degradation rate constant (k) of Aspirin was determined for each temperature setting. Log

k vs. 1/T was plotted. Using the Arrhenius equation, the degradation rate constant at 25C was

calculated.