Question

Which of the following pairs of aqueous solutions will form a precipitate when mixed? Which of the following pairs of aqueous solutions will form a precipitate when mixed?

a. CaS + Na₂SO₄
b. Li₂SO₄ + KOH
c. Li₂CO₃ + NaI
d. None of these solution pairs will produce a precipitate.
e. All of these solution pairs will produce a precipitate.

Answer 1

Upon using solubility rules, it is found that none of the solution pairs CaS and Na2SO4, Li2SO4 and KOH, or Li2CO3 and NaI will produce a precipitate. So the correct answer is d. None of these solution pairs will produce a precipitate.

Step-by-step explanation:

To determine which pairs of aqueous solutions will form a precipitate when mixed, one must use solubility rules. According to solubility rules, all compounds of Li+, Na+, K+, Rb+, Cs+, and NH4+, and all compounds of NO3− and C2H3O2− are soluble. By cross-combining the ions, we can predict if a precipitate will form. For the pairs listed:

• CaS and Na2SO4 will not produce a precipitate since all resultant compounds are soluble.
• Li2SO4 and KOH also will not result in a precipitate due to the solubility of all possible products.
• Li2CO3 and NaI might suggest a possible precipitate formation of LiI or Na2CO3, but both lithium iodide and sodium carbonate are soluble, so no precipitate forms.

Therefore, the correct answer is d. None of these solution pairs will produce a precipitate.