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Assay of Aspirin

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generose carumba

on 19 January 2014

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Transcript of Assay of Aspirin

5. The content of 20 aspirin capsule was dissolved in 100 ml of alcohol if a 10 ml aliquot was found to contain 0.4880 g of aspirin.

What was the percent of the labeled amount ( 5 gr ) of aspirin in the capsule.

and Answers

1. How is neutralized alcohol prepared?

Volumetric Flask
titration with base
Assay of Aspirin
Titration with acid
2. What is the reason of adding neutralized alcohol in the assay of ASA?

3. Give the purpose of heating ASA in the water bath with the use of an air ?

4. What is the type of titration involved in the assay of ASA?

Iron stand with Buret clamp
Graduated cylinder
Erlenmeyer flask
Filter paper
aspirin capsule
0.1 N sulfuric acid
0.1 N sodium hydroxide
nuetralized alcohol
STEP 1. Transfer, as completely as possible, the contents of not less than 20 Aspirin Capsules to a 100-ml volumetric flask, then Place the emptied capsules in a small beaker.

STEP 2. Add sufficient neutralized alcohol, and Agitate for 10 minutes.

STEP 3. Filter into the flask, Wash the beaker and filter well with cold neutralized alcohol, receiving the washings in the same flask.

STEP 4. Add cold neutralized alcohol to make exactly 100 ml, and Mix.

STEP 5. Transfer an accurately measured volume of the solution, Equivalent to about 500 mg of aspirin, to a conical flask.

STEP 6. Add cold neutralized alcohol, if necessary, to make about 20 ml.

STEP 7. Add phenolphthalein TS, and Titrate the solution immediately with 0.1 N Sodium Hydroxide (NaOH).
STEP 1. Add the titrated solution a volume of 0.1 N Sodium Hydroxide (NaOH) equal to that used in the titration, Plus 15 ml more.

STEP 2. And heat the mixture in a bath of boiling water for 15 minutes with frequent agitation.

STEP 3. Remove the flask from the water bath, Cool it quickly to room temperature, and Titrate with 0.1 N Sulfuric Acid (H2SO4).

STEP 4. Perform a blank determination with the same quantities of the same reagents and in the same manner.

STEP 5. Subtract the number of milliliters of 0.1 N Sulfuric Acid (H2SO4) Added the second time.
It was about 10% methanol, a bit of water and the rest ethanol and it was previously cooled to 15 to 20 °C.
To convert the substances for reaction with the standard base and to speed up the hydrolysis.
N= (Weight of sample)
(mL x mEq)
%= (mL x N x mEq x 100)
(Weight of sample)

100 mL
10 mL of aliquot
0.4880 g of Aspirin
5 gr = 0.0325 g
1 gr = 0.065 g
N= (Weight of sample)
(mL x mEq)
%= (mL x N x mEq x 100)
(Weight of sample)
= 0.4880 / (10 mL x 0.018016)
= 0.4880 / 1.8016
= 0.27087 N
= 100 mL x 0.27087 x 0.18016 x 100
0.325 g
= 1501.53658 %
= 1501.53658 % / 20
75.08 %

Residual Alkalimetry Titration
for Listening
to easily dissolve.
Full transcript