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Aspirin Purity Testing 2014

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Experiment for Organic Lab 10-7-14

So this video is going to deal with tests and aspirin purity and this falls on an umbrella of what we call characterization which is simply determining the identity of a chemical species in a couple of ways to characterization one is to use some type of physical tests like testing the melting point or the boiling point and we’ve done melting point already on aspirin

And compare it to a known number we can also do chemical tests like nmr and for a uv reactivity test or testing the ph so in a particular experiment for today we’re going to do two things when the test ph as well as test aspirin purity we’re just going to get three test tubes you’re going to put in one test tube you want to put your acid salicylic acid i’m sorry

One test tube you want to put your aspirin and then the commercial aspirin you’re going to test the ph by dipping the ph paper down into the test tube after you do that you’re gonna compare the color that you see on the ph paper with the ph color chart which is shown here the color chart tells you if something is highly acidic or if it’s basic and so at the end of

That part of the experiment what you want to ask is what can i say about the ph of my aspirin how does it compare to commercial aspirin and then how much salicylic acid content is present there’s a high salicylic acid content using means that the sample should be more sick so in the second part of the experiment what we’re going to do is test aspirin purity using

What’s called an iron chloride test normally if you are iron chloride any unreacted salicylic acid is going to react with iron chloride and that solution should turn purple so what we’re going to do is test to see if there’s any unreacted salicylic or salicylic acid sorry by adding a few drops of iron chloride our aspirin sample so here’s the aspirin synthesis we

Have salicylic acid reacting with acetic anhydride we have sulfuric acid as a catalyst and then here’s my aspirin and leftover or as a by-product is acetic acid so here we have some potential impurities that show up salicylic acid acetic anhydride and of course leftover acetic acid adding the iron chloride what we do is we’re able to detect any leftover salicylic

Acid because the iron chloride solution will turn purple when that solution turns purple depending on how deep the purple color is that’s gonna tell us how much salicylic acid is actually left over so here what we want to do is go back in here so the maximum amount of salicylic acid that’s allowed for commercially available aspirin is point one five percent so if

We compare the aspirin that we made to commercial aspirin if the astronaut we made is darker in color then that indicates that there’s more left over salicylic acid in that but in our aspirin than there is in the commercial aspirin and if that’s the case then our aspirin does not meet the necessary quality requirements so here’s the example of what the actual purity

Test was going to look like so if you look to the left you see commercial aspirin and then our synthesized aspirin and in all honesty we expect the synthesize asked them to be a little bit darker in color because the just equality and the purity standards are not as rigorous in an organic chemistry lab like they would be at bayer or some other aspirin manufacturer

And so we expect it to be darker so you can see even in this example the synthesized aspirin is a little bit darker than the commercial aspirin and so what we’re going to do is compare what we purify to the commercial brand ask the question is it lighter is it darker and then what can you conclude about the purity based on that is it less pure or is it as pure

As commercial aspirin so in summary what we’re going to do is compare commercial aspects are purified aspirin we’re going to take the ph of the commercial and the purified aspirin using ph paper and we’re going to compare that using a ph color chart to determine the ph of our aspirin we’re going to test the purified aspirin for purity using iron chloride which is

Going to tell us how much salicylic acid is actually left over there’s actually a really neat experiment that we could do using a spec 20 but we’ll probably have to do that another time and then we’re going to make a comparison of the aspirin that we synthesized versus the aspirin test that you can buy in the store and make those comparisons in your data section

You know was it really deep purple was it light purple did it almost match the purple color of the commercial aspirin i mean all those things you can talk about in your data section and then ask the final question is your aspirin safe to ingest the answers probably no and just as a disclaimer we’re not to ingest the aspirin that we made it’s not pure enough so

With that being say if you got any questions just shoot me an email thanks

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Aspirin Purity Testing 2014 By chemistryrussell