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Determination of Aspirin

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Determination of Aspirin

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  • Jan. 20, 2011
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Reshmi Nair
Title: Determination of Aspirin through back titration.
Aim: To determine the concentration of Aspirin in a tablet using NaOH and Hcl. Research Question: What is the concentration of Aspirin in a normal tablet?
Background:
Aspirin is the general name for acetylsalicylic acid (ASA); it is also the trademark of the drug produced by Bayer in Germany. In eighty countries, aspirin is a registered trademark, but in other places the term aspirin refers to ASA by itself or as an ingredient in other drugs.  The synthetic drug was developed as an analgesic (painkiller) and this is still the main purpose of the drug in most people’s minds. It was the first NSAID (nonsteroidal anti-inflammatory drug), and probably still the most effective. Back Titration: Back titration is an analytical chemistry technique that allows the user to find the concentration of a reactant of unknown concentration by reacting it with an excess volume of another reactant of known concentration.

Fig 1: Titration
http://qwickstep.com/search/titration.html
Variables:
Independent variables: mass of the Aspirin, Volume of Hcl
Dependent: Volume of NaOH
Controlled: Concentration of Hcl and NaOH,

Method to control Variation:
* By maintaining the temperature and pressure at Room Temperature. * Use the Hydrochloric acid in bulk so that the concentration of the substance will remain the same. * Use the same pipette and burette throughout the experiment. Apparatus:

* Burette
* Weighing Bottle
* Cylinder
* Flasks
Chemicals Needed:
* Hcl
* Phenolphthalein
* Sodium Hydroxide
Safety equipment:
* Lab Coat
* Safety goggles
* Lab gloves

Fig 2: Titration of an acid to a base by using phenolphthalein as the indicator.

Proceudre:
* Add 100 Ml of distilled water into a bottle
* Measure the approximate value of the Hcl using the Cylinder * Gradually add the acid into the water while stirring, until the volume of the total...