Organic synthesis
Read our general notes on Risk Assessment
If 2.00 g salicylic acid reacts with an excess of acetic anhydride, calculate the theoretical yield of acetylsalicylic aid for this synthesis.
First look up or work out the molar masses of salicylic acid and acetyl salicylic acid.
Next calculate the number of moles of salicylic acid that are represented by 2.00 g (i.e. 2.00/Mr).
Since - in theory - 1 mol of salicylic acid changes into 1 mol of acetyl salicylic acid (assuming an excess of acetic anhydride), the amount in moles you calculated for salicylic acid should be equal to the amount in moles of acetylsalicylic acid formed.
If you then multiply this value by the Mr for acetylsalicylic acid, you will have calculated the theoretical mass of acetylsalicylic acid which should have been obtained.
Please remember that for several reasons you are unlikely to have obtained this yield in practice. I hope that you know several reasons why this is the case!
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
Rate this page or react
Share your views on this page, 16 ratings so far
, rated at 
updated: 25 August 2003
