Video: Solubility of sulfates
The trend in alkaline earth metal sulfates is from MgSO4 (very soluble) to BaSO4 (highly insoluble. The thick, white precipitate of barium sulfate is formed when any soluble bariums salt is mixed with any soluble sulfate. The insoluble barium sulfate suspension is used in stomach X-rays as barium is opaque to X-rays.Ba2+(aq) + SO42-(aq) ® BaSO4(s)