Question

Silver iodide is a very insoluble compound. Please give reasons for compounds like silver sulfate or silver chloride to be insoluble that relate to ionic radius.

Answer 1

Silver fluoride is more soluble in water as it is ionic compound. Siver chloride which is less ionic is soluble in only with inducement of ammonia. There is increase in covalency in Silver iodide and it is insoluble.

As we go down the group in the periodic table, the ionic radius increases, and the solubility decreases. As the halide ions become bigger, their silver salts become even less soluble mainly as a result of the decreasing strength with which the halide ions are hydrated. This means that the concentration of halide and silver ions left in solution after one of the silver halide precipitations becomes even lower as the group is descended. With this ionic character decreases and covalent character increases.

So as we go down the group,the halogens show a decreasing attraction for water molecules (hydration) which tends to decrease oxidising power as we go down the group.

Silver sulfate is also less soluble. As solubility is a result of an interaction between polar water molecules and the ions of a compound. Ions which have larger charge magnitudes are less soluble.