Can you compare the lattice enthalpies of the salts #MgCl_2#, and #CaCl_2#, and #SrCl_2#, and #BaCl_2#?

Question

Caleb Adams · Accepted Answer

Neither #CsCl_2# nor #ScCl_2# exist..........

We could compare #MgCl_2#, and #CaCl_2#, and #SrCl_2#, and #BaCl_2#. Of these, #MgCl_2# will have the highest lattice energy. Why? Because #Mg^(2+)# is the smallest ion, and thus the electrostatic force of attraction is GREATEST between the smaller metal cation and the chloride anion. And certainly, given the #1/r^2# electrostatic force, interaction between the cation and the anion will be here the most significant.

Cameron Andrews · Answer

undefined The lattice enthalpies of the salts MgCl2, CaCl2, SrCl2, and BaCl2 generally increase as you move down the group from Mg to Ba due to increasing ionic radius and stronger electrostatic interactions between ions. Therefore, BaCl2 would have the highest lattice enthalpy, followed by SrCl2, CaCl2, and MgCl2.

Noah Aldrich · Answer

undefined The lattice enthalpies of the salts MgCl2, CaCl2, SrCl2, and BaCl2 follow the trend:

BaCl2 > SrCl2 > CaCl2 > MgCl2

This trend occurs because lattice enthalpy decreases with increasing cation size due to weaker electrostatic interactions between the cation and anion in the crystal lattice. Therefore, BaCl2 has the highest lattice enthalpy, while MgCl2 has the lowest.