we are adding phosphate metal precipitates (e.g. FePO4(s)) to a 0.1 M PO4 buffer ph 7.4, need to know how fast the solid will dissolve over a time span of 30-60 min
I go for the supremacy of entropy. Therefore I would say dissolution is faster, tough hydration of PO4 is an extrastage. On the other hand precipitation sometimes is very fast (depends on Kps). I bet you that FePO4 crystalize faster than Al2HPO43. One thing is Kps and a different one is solvation.