Question

A pure white crystalline compound was found to melt at 112.5-113.0oC when taken on a melting point apparatus, and on further heating, the liquid was found to turn brown at ca. 145-150 oC. The capillary containing the melted compound was set aside to cool, and resolidify. When the sample was retried, using the same capillary the sample melted at 133.6-154.5oC. Why is the melting point higher than 112°, and the range so wide?

Answer 1

According to the question, the determined melting point of the compound is 112.5-113.0oC. When the solidified compound was retried, the melting point was found to be 133.6-154.5oC. This greater range higher than  112°C is caused by reusing samples leads to errors.

A pure sample is known by its sharp melting point. A pure sample does not melt over a large range. We can see this in the predetermined melting points of the pure sample(112.5-113.0oC).

However, reusing a sample introduces errors because the pure sample may become contaminated leading to a larger and higher range of melting point (133.6-154.5oC) which is far above  112°C.

Learn more: brainly.com/question/5325004