A student performs twomelting point determinations on a crystalline product. In onedetermination, capillary tube contains a sample about 1-2 mm inheight and the melting point range is found to be 141-142C. In the other determination, the sample height is 4-5 mm and themelting range is found to 141-145C. Explain the broader meltingpoint range observed for the second sample. The reported melting point for the compound is 143C.