Question

the correct order of the lattice energies of teh following ionic compounds is
a) Nacl>MgBr2>CaO>Al2O3
b)Al2O3>MgBr2>CaO>NaCl
c)MgBr2>Al2O3>CaO>NaCl
d)Al2O3>CaO>MgBr2>NaCl
please answer this question fastly
I want it fast I want correct reason

Answer 1

As we go across a period, the ionic charges increase. Due to this the lattice enthalpy or charges also increase. Hence lattice energy of Al > Mg > Na.

Also as we go down a group ionic size only increases but charge remains same. Hence as we go down a group, lattice energy decreases.

=> Li > Na > K

No we can first arrange the cations in the question.

Given Cations are : Na, Mg, Ca, Al

We know that, Al > Mg > Na

Also Mg > Ca

=> Correct order of decreasing lattice enthalpies are :

Al > Mg > Ca > Na

=> Option ( b ) has the same criteria.

Hence Option ( B ) is correct option.

Al₂O₃ > MgBr₂ > CaO > NaCl.