Titration
The titration technique for estimating the purity of aspirin also had its good points and bad points. The good points were that this technique provided accurate results to decimal places. Also by this technique you can find out how much sodium hydroxide it would take to neutralise a sample of aspirin; this is also a good point. The bad points to this technique however were that it consumes too much time and in the meantime a lot of human-errors can occur. Also another bad point to this technique was that the results acquired are dependent on a lot of factors; such as the diluting substance you use and also the indicator you use.
Melting Point
The melting point can also be used to measure the purity of a sample of aspirin because a pure sample of aspirin usually has a small temperature range during which it changes from a solid to a liquid. An un-pure sample will tend to melt over a range of degrees. I feel this technique is good because it is really quick and simple. However there is still chance for human error, if the temperature is not read correctly.
Conclusion
In conclusion I feel that the melting point was the best and the most accurate method of estimating purity of aspirin. This is because it does not consume much time and also it is really easy and simple. All that needs to be done is read the temperatures and it will show you whether the sample of aspirin is pure or not.
TLC Plate Chromatography
This method I think was fairly accurate because it showed the difference between the pure and the impure sample of aspirin. However it can’t be exactly precise to the percentage of purity. The results which I obtained from the chromatography could have been fairly accurate to a certain point however there are a few potential drawbacks that could affect the accuracy of the results. These are; the TLC plate could have another solution already placed on it. This would mix with the aspirin solution causing the experiment to be inefficient. Another reason for the results to not be as accurate is if I placed my fingers on the actual base on the chromatography paper. This would infer my results.
Titration
This technique could have a few human errors included which would affect the accuracy of the results obtained. The errors which could possibly occur:
If the burette and beakers are not rinsed each time they use a different substance, there is a high chance of contamination.
Also to reduce the risk of contamination, distilled water has to be used to rinse the glassware
The human eye may not be able to read of the exact end point result
The amount of the phenolphthalein indicator used could either be too much or too less for the practical experiment
Therefore basically for the titration practical’s you have to ensure to get accurate results you look closely at any measurements
Melting point
The melting point technique is fairly accurate however it could also lack errors. If I did not know of the actual melting point of a particular substance and I just tried random temperatures, it could tamper with the substance and my results. Whilst reading the temperature you might read it a few degrees above or a few degrees below. This would not melt the substance properly and wouldn’t provide you with accurate results.
None of the results I obtained will be absolutely accurate because there could have been some sort of errors which occurred. I evaluated the techniques I used and discussed where they could lack in accuracy.
by
serhad1234hotmailcouk (student)
