What would be observed in the addition of barium nitrate to magnesium sulfate? What about for barium nitrate and postassium iodide?
Macroscopic changes depend on solubility equilibria.
Barium nitrate and magnesium sulfate:
Barium sulfate is quite insoluble in water. A white solid precipitates.
Barium nitrate and potassium iodide:
Both metathesis products,
Lead nitrate and barium nitrate: no macroscopic change.