Question

7. Salts-ionic compounds-also exist in solid form, and ionic charges hold them together. (That should trigger some Coulomb's Law flashbacks...) Based on this, rank the melting points—1 for the lowest melting point to 5 for the highest melting point-for the substances below. Remember to consider both the magnitude and the distance separating (i.e., size of) the ions. NaCl RbBr NaBr KI KBr Propose a chloride salt with chemical formula XCl that has a higher melting point than any of these. In a sentence or two, explain your choice. Propose a rubidium salt with chemical formula RbX that has a lower melting point than any of these. In a sentence or two, explain your choice.

Answer 1

solution: Melting point order of the queen ionic compounds: KI < RbBr c k Br < Na Br < Nach į 2 3 4 5 Explaination: 1. According to fajan's Rule: large size of abrion, small size of cation makes high covalent character in the compound. anion - Polarisation on size of Anion Covalent of I size of cation character melting point! Note : size of capion doncinates over size of cation. kl has higher melting point than any of these - size of do is small in comparison of Io Bro 4 also size of xt is larger then Nat. => Rb I will have lower boiling | melting point because I being greater in size leads to high polarisation according to fajan's Rull. Scanned with CamScanner