Are all dissolution reactions spontaneous?

Oh I see. So all dissolution reactions are spontaneous reaction (delta G < 0)?

Yes if something will dissolve the dG is negative (dG actually only indicates the equilibrium position between the dissolved and pure substance, for all dG except in the limit of infinitely disfavourable, there will be some dissolution of the solute). Because of the nature of the expression for dG (dG=dH-TdS), G changes with T as dissolution is highly favourable in terms of entropy. This is why things dissolve more readily at higher T.

Oh I see. So all dissolution reactions are spontaneous reaction (delta G < 0)?

All reactions, both chemical and physical are spontaneous. If they weren't spontaneous they could not happen ...

but they are only spontaneous under certain conditions surely?

admittedly, the difference between spontaneous and feasible has had me stumped recently. any thoughts?

True, but any reaction that actually happens MUST be spontaneous.

There are only two criteria for reaction, thermodynamic and kinetic.

A process could be spontaneous, but not happen because of kinetic control, BUT it cannot be non-spontaneous and still happen ...

You can force a reaction by doing electrical work.