Which of the following aqueous solutions
should NOT form a precipitate with aque-
ous Ba(NO3)2?
1. K3PO4
2. K2SO4
3. K2CO3
4. KOH
KOH
KOH
To determine which of the following aqueous solutions should not form a precipitate with aqueous Ba(NO3)2, we need to refer to a solubility table.
A solubility table provides information about the solubility of common compounds in water. It tells us whether a compound is soluble (dissolves) or insoluble (forms a precipitate) when mixed with water.
In this case, we are interested in the solubility of compounds that contain the ions PO4^3-, SO4^2-, CO3^2-, and OH-. We want to find the compound that does not form a precipitate (insoluble) when mixed with Ba(NO3)2.
1. K3PO4: Looking up the solubility of phosphates in a solubility table, we find that most phosphates are insoluble, including Ba3(PO4)2. So, when Ba(NO3)2 is added to K3PO4, it should form a precipitate. Therefore, K3PO4 is not the correct answer.
2. K2SO4: Sulfates (SO4^2-) are generally soluble except for a few exceptions like PbSO4, BaSO4, and SrSO4. Although BaSO4 is insoluble, in this case, we are adding Ba(NO3)2 to the solution, not BaSO4. Thus, the presence of K2SO4 should not cause a precipitate. Therefore, K2SO4 is a potential correct answer.
3. K2CO3: Carbonates (CO3^2-) are typically insoluble except for Group 1 cations (Li, Na, K, Rb, Cs) and NH4+. Ba^2+ is not one of those cations, so when Ba(NO3)2 is added to K2CO3, it should result in a precipitate. Therefore, K2CO3 is not the correct answer.
4. KOH: Hydroxides (OH-) are typically slightly soluble, with some exceptions like Group 1 hydroxides (LiOH, NaOH, KOH, RbOH, CsOH) and alkaline earth hydroxides (Ba(OH)2, Sr(OH)2, Ca(OH)2). Since Ba(OH)2 is already present in the form of Ba(NO3)2, the additional KOH should not form a precipitate. Therefore, KOH is another potential correct answer.
In conclusion, the potential correct answers that should NOT form a precipitate with aqueous Ba(NO3)2 are K2SO4 and KOH.