Question

The ideal MP of benzophenone is around 47.9°C while the starting material benzhydrol MP should be around 65-67°C. If your final isolated products was in fact a mixture of 90% benzophenone and 10% benzhydrol starting material by weight, what would be the likely MP range and why?

Answer 1

Mixed melting points tends to be lower (or higher depends on the mixture composition) than the actual melting point of pure compounds. This is due to the fact that less number of attractive forces exists between the molecules of the same type and thus less heat is required to melt the compound.

When 90% benzophenone (m.p. 47.9 oC) was mixed with 10% benzhydrol (m.p. 65-67 oC), the resulting melting point would be closure to benzophenone melting point. Approximate melting point of the mixture could be 50-56 oC. This is a prediction only. The actual melting point could be very different from this one.