Question

Which of the following pairs of 0.1 M aqueous solutions would result in the formation of a precipitate upon mixing?

a) NaCl and KNO3
b) AgNO3 and Na2S
c) HCl and NaOH
d) NH4Cl and NaBr

Answer 1

The pair AgNO3 and Na2S from the options given would result in the formation of a precipitate upon mixing because Ag2S (silver sulfide) is insoluble in water.

Step-by-step explanation:

To determine which pairing of 0.1 M aqueous solutions would result in the formation of a precipitate upon mixing, we use solubility rules to predict precipitation reactions. When the ions from two different solutions are mixed, they can form new ionic compounds, some of which may be insoluble in water and hence precipitate out of solution.

Looking at the options provided:

• NaCl and KNO3: Both Na+ and K+ form soluble compounds with Cl- and NO3-, so no precipitation reaction occurs here.
• AgNO3 and Na2S: Ag+ and S2- would form Ag2S, which is insoluble in water, and thus a precipitation reaction is expected to occur.
• HCl and NaOH: This is a neutralization reaction, not a precipitation reaction, and would result in the formation of water and soluble NaCl.
• NH4Cl and NaBr: Both NH4+ and Na+ form soluble compounds with Cl- and Br-, so no precipitation reaction occurs here.

Therefore, the pairing that results in a precipitate upon mixing is AgNO3 and Na2S, with the insoluble salt formed being Ag2S (silver sulfide).