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Making Aspirin

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In this task we were asked to synthesise aspirin from salicylic acid (2 - hydroxybenzoic acid) and ethanoic anhydride (CH3COOCOCH3) in a laboratory scale and prepare a pure silver chloride sample from the solutions of silver nitrate (AgNO3) and sodium chloride (NaCl) of known concentrations. Now I am going to describe the preparation of these two items and estimate the purity of one of my samples. Preparation of aspirin: Now I am going to explain the preparation of the aspirin; Materials : (a) ethanoic acid (b) ethanoic anhydride (c) salicylic acid (d) water cooled condenser (e) filter paper (f) Buchner funnel (g) vacuum oven (h) melting point recorder machine etc. Procedure 1) Firstly we mixed 5 ml of ethanoic acid with 5 ml of ethanoic anhydride in a 50 ml round bottomed flask. 2) After that we added 5 g of 2- hydroxybenzoic acid and a few anti - bumping stones . 3) Then we attached a water cooled condenser and reflux the mixture for 30 minutes over a Bunsen and gauze. 4) Then we pour the mixture slowly into 100 ml of cold water which is being stirred vigorously. 5) After that we removed the 2 - ethanoyloxybenzoic acid by filtration through a Buchner funnel. 6) Then we removed the product from the fume cupboard and dried it in a vacuum oven at about 80 degree Celsius. ...read more.


= 0.1435 g. Step 3: Now I am going to calculate the % yield from the results we have already got. Estimate the purity of aspirin: We can find the purity of any substances by determining the melting point which is the book value. The melting point of aspirin is about 1360 C which is the book value. The aspirin we made in the experiment was kept in the melting point apparatus to find out its melting point. The melting point apparatus which has a heating block inside to heat the sample. A small glass window in front of one instrument through which we can see what we put inside the instrument. There is a small block on top of the instrument with three holes in which we can put the capillary tube filled with the sample. One end of the capillary tube is sealed. There is a place at the back of the capillary tube slot to insert the thermometer. I took a little bit of sample in the capillary tube and put it inside the melting point apparatus. Then I switched the machine on and used the heating and lamp option to heat the sample slowly. After a while when the temperature was 1280 C to 1290 C the colour of the aspirin was changing and it started to melt and its melted completely about 1310 C temperature. ...read more.


In the 2nd experiment we had to put 5g of salicylic acid in the mixture, so we had to do that perfect as well. If we haven't done them right, the purity of the products will not be quite satisfactory. Reaction time: The reaction time of any reaction should be done with care. If the reaction time is so quick or so slow then the produced products will not be pure enough to deal with. That's why we have to make sure that we have done these things right to get the pure products. How to improve them: To improve these things explained above, we have to follow some steps involved; First of all we have to make the work plan to do this experiment right. Then we have to follow the plans. Then we have to follow the procedures and steps involved in the experiment. We have to make a list of what might go wrong in the experiment and then we have to do them carefully. We have to make sure that when we keep this solid products in the oven, that nobody can open them for a minute or something, then the purity will be very bad. All the major factors involved in this experiment, we have to do them perfectly and by making the work plan, and by applying it correctly we can easily improve this experiment and get more products yield and more purified. ?? ?? ?? ?? Page 1 ...read more.

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Response to the question

The student sets out his/her answer very clearly and logically and therefore, the answer has been attempted in a logical and sensible manner. The response is very explicit and clear. The explanations in the calculations section is perfect and guides ...

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Response to the question

The student sets out his/her answer very clearly and logically and therefore, the answer has been attempted in a logical and sensible manner. The response is very explicit and clear. The explanations in the calculations section is perfect and guides the reader (examiner) through the process very clearly. The only area I can fault in this piece of work is the lack of referencing. Although all chemists know what is meant by "book value", perhaps it is best to reference where this value came from (in this case, as referenced in the textbook that the student has for their exam board). Also any diagrams must be sourced and referenced as this stops any infringement of copyright from occurring in this piece of work.

Level of analysis

The student shows a very clear understanding of the topic and analyses the topic well. S/he supports the topic well with explanations to each step of the experiment and calculations that followed on from the experiment. Their judgements are clear and suitable from the experiment and the appropriate conclusions were reached. I would suggest that they had laboured the word 'we' in the piece of work - instead of "we add" just write "add". This makes the coursework more 'formal' and suitable for the level of qualification in my view.

Quality of writing

The spelling, grammar and punctuation were fine. I would suggest using bullet points to clearly space out of the sub sections, although this is personal preference which I think would make each point clearer and easier for examiners to read. This said, the piece of work is presented clearly nevertheless. The technical terms could be defined in a glossary to demonstrate further understanding, although again this is not compulsory. The student exceeds the expectations of this level of work as they have explained each step very clearly and obviously has a very solid understanding of the topic. On a last note, I would say that the formatting for 'degrees C' should be relooked at as the format should not be a 'zero' as a superscript with a capital 'C'.

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Reviewed by crystalclearmagic 22/03/2012

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