Final answer:
When Ba(OH)2 and MgSO4 are mixed, BaSO4 is likely to precipitate given its low solubility. Mg(OH)2 could potentially precipitate as well, but this depends on the specific concentrations present in the solution. Therefore, the answer could be either BaSO4 alone or both BaSO4 and Mg(OH)2.
Step-by-step explanation:
When aqueous solutions of Ba(OH)2 (barium hydroxide) and MgSO4 (magnesium sulfate) are mixed, a precipitation reaction may occur. The question is whether a precipitate forms and, if so, what it is. Based on solubility rules, BaSO4 (barium sulfate) is an insoluble compound and is likely to precipitate when these two solutions are mixed.
The relevant chemical reactions would be:
- Ba(OH)2 (aq) + MgSO4 (aq) → BaSO4 (s) + Mg(OH)2 (aq)
- Ba2+ (aq) + SO42- (aq) → BaSO4 (s)
However, because Mg(OH)2 is also only slightly soluble, it is possible for it to precipitate as well under certain conditions. In this case, the presence of sulfate ions (SO42-) from MgSO4 provides the counterion necessary for the precipitation of BaSO4, while the barium ions (Ba2+) could potentially provide the counterion for Mg(OH)2 precipitation if the concentration of OH- is high enough. Given this information and without additional data on concentrations, it is not possible to definitively state whether or not magnesium hydroxide would also precipitate. The most likely precipitate to form immediately upon mixing these two solutions is BaSO4, as it has a lower solubility product (Ksp).
Thus, the correct answer to the student's question would be either option 3 (only BaSO4) or option 4 (both BaSO4 and Mg(OH)2), depending on the concentrations involved in the actual reaction mixture.