# Analysis Of Aspirin Tablets

Purpose:

Determine the percentage of 2-ethanoylhydroxybenzoic acid in aspirin tablets.

Introduction (including background information) :

Before creating Aspirin, “sail alba” was used. In 1860’s, chemists discovered that Salicylic acid (2-hydroxybenzoic acid, C7H6O3 ) is the active acid in sail alba. Salicylic acid is relatively strong though. It can irritate and damage the stomach membranes and mouth.

In 1889, ethanoate ester of salicylic acid was introduced by the Bayer Company. They named it Aspirin. Aspirin is an analgesic and antipyretic drug. Analgesic drugs relieve certain types of pain, such as headaches. Antipyretic drugs lower body temperature rapidly if it is high. Aspirin doesn’t damage the stomach

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Aspirin passes unchanged through the acidic conditions in the stomach, but is hydrolyzed to ethanoate ion and 2-hydroxybenzoate ions by the alkaline juices in the intestines.

Aspirin is a monoprotic acid (Monoprotic acids are acids that can donate one proton per molecule during the process of ionization). Therefore, aspirin can react with NaOH (sodium

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This causes the uncertainties of the volume added to be identical between all readings.

To find the uncertainty of volume added, you add the uncertainties of the final and initial readings which gives us the formula (formula nr.2) Uncertainty of final reading + Uncertainty of initial reading = Uncertainty of volume added

So the uncertainty of the results is 0.1 because 0.05 + 0.05 = 0.1

I found the average by adding all the values and dividing them by the number of values which gave me the formula (formula nr.3)

addition of values / number of values

So let’s use table 1 as an example:

(25.1 + 25.1 + 25.1 + 25.0 ) / 4 which gives up 25.075

To find the uncertainty of the result above (25.075) we have to find the percentage uncertainty first.

(formula nr.4) % uncertainty = ( “uncertainty in volume” / volume) x100 for example 25.1 ± 0.1 so % uncertainty = 0.1/25.1 * 100

= 0.398 so rounded to 0.4%

now we add all percentage uncertainties:

0.4 + 0.4 + 0.4 + 0.4 = 1.2

so we have 25.075 ± 1.2%

Now we can use the formulas and values above to find the concentration of NaOH the concentration of NaOH added is approximately 1.0 mol