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- Apr 8, 2011
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So today I was in the lab and we had to identify an unknown via the melting point. The melting point of my unknown was 121 degrees celsius. I tested a mixture with napthene, the impurity caused it to melt at 85 degrees celsius. I tested it with mendelic acid, it melted at 94 degrees celsius. I tested it with Benzoic acid, it melted at 113 degrees celsius. Then I went out of the range and tested every substance within 10 degrees of the melting point and formed a mixture, still couldn't identify it. I finally smelled it and noticed a distinct pistaccio/almond smell. I saw the same distinct smell with the mendelic acid. I then retested the Benzoic acid with the unknown and it melted at 121 degrees celsius HOWEVER!!! the sample mixture was about 90% benzoic acid which melting point is 122 and 10% unknown due to my limit on my unknown. We also only tested a few micrograms of the mixture.
My question: Should I rely on the melting point of the mixture that was 90% benzoic acid and had a completely different smell than the unknown, OR should I rely on the smell and go with the mendelic acid regardless of the obvious depression of the melting point upon mixture.
Thanks in advance!
My question: Should I rely on the melting point of the mixture that was 90% benzoic acid and had a completely different smell than the unknown, OR should I rely on the smell and go with the mendelic acid regardless of the obvious depression of the melting point upon mixture.
Thanks in advance!
