entholpies of solution

are they endo or exothermic

They are exothermic so always negative

how to calculate △solH

positive enthlopy add on △hydH

how does ionic charge affect △hydH

Ions with a greater charge have a greater △hydH as they are better at attracting water molecules

how does ionic radius affect △hydH

smaller ions have a greater △hydH as they have a higher charge density so attract water molecules better

Why is it hard to predict whether the enthaloy change of solution becomes more or less exothermic down group 7

Halide ions get larger down the group. Enthalpy change of hydration is less exothermic down the group so water is less attracted to the halide ions down the group. Lattice enthalpy is less exothermic down the group so difficult to predict whether lattice enthaloy of hydration enthalpy has a greater effect