Question

Three test tubes contain white crystalline organic solids A, B, and C, each of which melts at 149-150 degrees C. A 50-50 mixture of A and B melts at 130-139 degrees C. A 50-50 mixture of A and C melts at 149-150 degrees C. In what range would a 50-50 mixture of B and C probably melt? What can you say about the identities of A, B, and C?

Answer 1

Answer:

The mixture of B and C will melt as 130 - 139 ºC.

Explanation:

If the melting point (130 - 139 ºC) of a mixture of A and B is lower than the pure substances that is 149 - 150 ºC that means that one of these susbtances is an impurity because reduces the melting point.

If the melting point of the mixture of A and C is the same as the pure substances, we can deduce that they are the same substances, also because the melting point when a substance is pure is just 1 or 2 ºC like in this case.

So in a Mixture of B and C is going to be like the first case of the mixture among A and B, because the B substance is the impurity.