Question

Sodium chloride melts at 1074k, magnesium oxide melts at 3125k.Both have identical structures why is there such a difference in their melting points?

Answer 1

Answer: NaCl has less lattice enthalpy than MgO. So MgO needs more energy melt.

Explanation:

LAttice Enthalpy is directly proportional to product of changes of the positive and negative ions.

For NaCl it is 1*1=1

For MgO (Mg++ and O--) it is 2*2= 4