Answer to Question #95424 in General Chemistry for Egba

Question

An unidentified compound is observed to melt sharply at 111 oc with the vigorous evolution of a gas. The sample then solidified and does not melt until the temperature reaches 155 oc, at which time it again melts sharply. Briefly explain these observations.

Answer 1

It’s possible the unknown compound is an impure compound. If this is the case, the impure compound

initially melts at 111 °C and the impurity leaves the compound in a gaseous state. The now pure compound

solidifies and melts again at 155 °C.