Question

Melting Order of: Bef2, MgF2, CaF2, SrF2, BaF2​

Answer 1

  The melting order of the alkaline flourides is as follows:

• CaF2>MgF2> SrF2> BaF2>BeF2​

Rules and Conditions for comparing the Melting order are:

• The melting order of a compound generally depends on the size of the cation and the size of the cation.
• It also depends on the lattice enthalpy and hydration energy of the compounds.
• Size of the cation in given compounds are +2 for Ca,Mg,Ba,Sr,Be where as the size of the anion is -1.
• From the properties of atomic radius , on moving down the group the size of the cation increases with the same charge.
• Since the density of Calcium is smaller than magnesium and the hydration enthalpy of Beryllium is very high on account of smaller size.
• A compound with smaller size has lower melting points.
• Beryllium is the smallest element in the group , so it has the lowest Melting point.
• Therefore , on considering all the conditions mentioned the final order is:  CaF2>MgF2> SrF2 >BaF2​> BeF2