when 0.1M solutions of the following substances are mixed, which pair will precipitate?
1) Pb(CH3COO)2 and Mg(NO3)2
2) H2SO4 and KOH
3) ((NH4)2)CO3 and Na3PO4
4) NaOH and BaCl2
5) CaCl2 and Na2CO3
To determine which pair will precipitate when 0.1M solutions of the given substances are mixed, we need to consider the solubility rules of common ions. Here's how to approach each pair:
1) Pb(CH3COO)2 and Mg(NO3)2:
To determine if a precipitate forms, we need to know if the combination of ions in solution will form an insoluble compound. Both lead(II) acetate (Pb(CH3COO)2) and magnesium nitrate (Mg(NO3)2) are soluble in water, so no precipitate will form.
2) H2SO4 and KOH:
Sulfuric acid (H2SO4) is a strong acid, and potassium hydroxide (KOH) is a strong base. When a strong acid reacts with a strong base, they neutralize each other to form water and a salt. In this case, no precipitate will form.
3) ((NH4)2)CO3 and Na3PO4:
Ammonium carbonate ((NH4)2CO3) is soluble, except when paired with certain cations like calcium, barium, and strontium. Sodium phosphate (Na3PO4) is also soluble. Since neither compound forms an insoluble compound in this combination, no precipitate will form.
4) NaOH and BaCl2:
Sodium hydroxide (NaOH) is a strong base, and barium chloride (BaCl2) is also soluble in water. When we mix them, a white precipitate of barium hydroxide (Ba(OH)2) will form since it is insoluble. Hence, this pair will precipitate.
5) CaCl2 and Na2CO3:
Calcium chloride (CaCl2) is soluble, but sodium carbonate (Na2CO3) is insoluble except when paired with certain cations like sodium and potassium. Since both compounds are soluble in this combination, no precipitate will form.
Therefore, the pair that will precipitate when 0.1M solutions are mixed are NaOH and BaCl2 (option 4).