Question

Why is melting point of kcl greater than agcl although crystal radii of k+ and ag+ are same?

Answer 1

K+ is larger than Na+ so NaCl has a higher lattice energy and a higher melting point than KCl. The Ag+ ion is intermediate in size between Na+ and K+. ... When the relative electronegativity of the anion and cation are very different as in NaCl and KCl, the bonding is predominately ionic.

Answer 2

The melting point of KCL is more than all even though crystal radii of k+ and ag+ are the same as:

Given:

• Given that cation sizes are almost the same, The cations are
• K⁺ and Ag⁺.
• K⁺ = [Ar] even as Ag⁺ = [Kr]4d¹⁰.

Explanation:

• K+ is greater than Na+ so NaCl has better lattice power and a better melting factor than KCl.
• The Ag+ ion is intermediate in length among Na+ and K+.
• When the relative electronegativity of the anion and cation are very distinctive as in NaCl and KCl, the bonding is predominately ionic.
• By searching on the e− configurations, K⁺ has a noble gas configuration and  Ag⁺ has a pseudo noble gas configuration due to stuffed d-orbitals.
• Such pseudo-noble gas configurations result in extra polarizing energy due to the useless defense of d-electrons. Thus Cl⁻ is extra polarized withinside the case of AgCl.

Thus, Agcl is extra covalent than KCI and as a result, has a lesser melting point.

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