Barium sulfate, BaSO4, is used in medical imaging of the gastrointestinal tract because it is opaque to X rays. A barium sulfate solution, sometimes called a cocktail, is ingested by the patient, whose stomach and intestines can then be visualized via X-ray imaging. If a patient ingests 400 mL of a saturated barium sulfate solution, how much toxic Ba^2+ ion has the patient consumed?
The solubility product Ksp of BaSO4 is 1.10x10^-10.
Express your answer to three significant figures and include the appropriate units.