Selected physical data for three crystalline oxides are provided in the table
CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
Selected physical data for three crystalline oxides are provided in the table.
Compound
Lattice Energy (kJ mol⁻¹)
Observed Melting Point (°C)
NaCl
787
801
MgO
3795
—
CaO
3414
—
Use the information to answer the following questions.
(a) Using only the data in the table, rank the three compounds from lowest to highest expected melting point.
(b) Explain the reasoning behind your ranking, explicitly connecting the numerical data to the physical changes that occur during melting.
(c) Assume, as a rough approximation, that the melting point of an ionic solid is directly proportional to its lattice energy. Using this proportionality and the data provided, estimate the melting point of MgO to the nearest 100 °C.