posted by Yoo .
I did a lab about melting point. It is asking me for the purity of the compounds?
How do I find it?
Do I use melting points or percent yield?
How sharp the melting point is and how close to the accepeted melting point the value you find are indicators of how pure the sample might be. Thus a sharp melting point that agrees with the accepted value would indicate a high purity sample.
Even better would be to have a pure sample and the test sample together in the same apparatus, and if these melt at the same time then this is a good indicator that the test sample is pure.
Percentage yield is not a good indcator of purity. I have carried out many a reaction where the yield was low, say 30%, but the product was pure.