In every chemistry lab we are taught that mixtures of compounds are going to have melting points lower than either of the components pure melting points.
Is this always true? Or can there be ratios of compounds that would generate a melting point above one pure compound and below the other?
For example, lets take acetanilide (MP: 114 C) and mix it with sodium acetate salt (MP: 324 C) in varying ratios. What would the melting points be for these?
1.) 98% acetanilide, 2% sodium acetate (slightly below 114?)
2.) 75% acetanilide, 25% sodium acetate (slightly above 114?)
3.) 50% of each (significantly above 114?)
4.) 25% acetanilide , 75% sodium actate (below 324?)
5.) 2% acetanilide, 98% sodium acetate (slightly below 324?)
NOTE: I chose these two compounds completely arbitrarily. Perhaps there is literature that has examined melting points for varying ratios of two particular compounds?
Follow up question:
Does there exist a mixture and/or ratio of solids that intermolecularly bond so strongly to each other that the melting point of that mixture is higher than the melting point of the individual components? What about a specific azeotrope with a higher boiling point than the liquids that make it up?