Answer to Question #299612 in General Chemistry for mela

Question

A student obtained a solid product in a laboratory synthesis.To verify the identity of the solid,she measured its melting point and found that the material melted over a 12^degree C range.After it had cooled,she measured the melting point of the same sample again and found that this time the solid had a sharp melting point at the temperaturr that is characteristic of the desired product.Why eere the two melting points different?What was responsible for the change in the melting point?

Answer 1

The initial solid contained the desired compound in an amorphous state, as indicated by the wide temperature range over which melting occurred. Slow cooling of the liquid caused it to crystallize, as evidenced by the sharp second melting point observed at the expected temperature.