CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
Four common solids—S₈ (rhombic sulfur), Fe, Al₂O₃, and Si—are placed separately in identical crucibles and heated steadily from 300 K to 2200 K at 1 atm pressure. During the heating process, an observer records the temperature at which each sample first begins to melt and the temperature at which each sample first begins to boil.
(a) Rank the four substances from lowest to highest melting point, based on their known structures and bonding.
(b) Rank the four substances from lowest to highest boiling point. If any pair is too close to distinguish given typical experimental uncertainty (±50 K), indicate this clearly.
(c) Explain the differences, if any, between the two rankings you produced in parts (a) and (b), making explicit reference to the types of forces that must be overcome in melting versus boiling.