Question

You have an unknown with an observed melting point of 90-93°C. Is your unknown compound A with a reported melting point of 95.5-96°C or compound B with a reported melting point of 90.5-91°C? Explain.

Answer 1

I would think your compound is compound A. Compound A with a small amount of impurity will cause it to have a lower melting point in the range of your m.p. AND to be less sharp. I wouldn't think it would be compound B because the melting point of your unknown is ABOVE mp of compound B and your unknown as range not nearly as sharp as A or B. Impurities cause mp to be lower, not higher.

Answer 2

The compound is most likely to be A.This is because Sample A containing little impurities will cause a reduction in its melting point not an increase as it would apply for Sample B.