Melting Point Determination

1. In a mixture of approx. 20% camphor and 80% naphthalene.  What would you expect the melting point to be?
(+/-)camphor (175-177 Celsius) and naphthalene (80-81 Celsius).

2. Describe the expected type of error in the observed m.p. (unaffected, high, low and /or broad) when the melting point is determined as follows.
   a. A Mel-Temp is used and the rate of heating is 15 Celsius/min.
   b. An excessively large sample size is introduced into the capillary tube before using the Mel-Temp.

3. Decide whether the statement is always true.  If not, explain when the statement would not be true.
    a. An impurity always lowers the melting point of an organic compound.
    b. A sharp melting point for an organic substance always indicates a single pure compound.
    c. If mixing a sample of compound A with compound X gives a lower melting point than compound X alone, then X and A cannot be identical.