Eplain the term polarising power of an ion and use it to account for the fact that AlCl3, sublimes at 451K....

Question

while KCl boils at 1680K

Answer 1

Al3+ is small and highly charged, and polarises the Cl- ions to such an extent that the bonding is largely covalent in AlCl3. This seriously reduces the attractive forces compared with an ionic substance such as KCl.