Question

Consider the following information:

Pb(NO₃)₂ and NaCl are both soluble salts that make colorless solutions consisting of the free ions, Pb₂+, NO₃, Nat and Cl.

All nitrate salts are soluble, as are most halide salts, except for those of silver, lead, and the

mercurous ion.

Which of the following evidence of chemical reaction may occur if solutions of Pb(NO3)2 and NaCI

are mixed?

a.formation of a precipitate

b.color change

c.evolution of a gas

d.temperature change

Answer 1

Mixing solutions of Pb(NO3)2 and NaCl leads to the formation of a precipitate, which is the insoluble compound PbCl2, indicating a chemical reaction.

Step-by-step explanation:

When solutions of Pb(NO3)2 and NaCl are mixed, a chemical reaction may occur that produces a precipitate. According to the given information, all nitrate salts are soluble, and most halide salts are soluble as well except for those of silver, lead (Pb2+), and mercurous ions. In this case, while the sodium nitrate (NaNO3) that forms will stay in solution due to the solubility rules, lead chloride (PbCl2) is expected to form an insoluble precipitate because lead halides are not soluble.

The predicted chemical reaction is:
Pb(NO3)2(aq) + 2 NaCl(aq) → PbCl2(s) ↓ + 2 NaNO3(aq)

This reaction is an example of a double displacement reaction where the cations and anions switch partners, resulting in the formation of one insoluble compound (precipitate) and one soluble compound. Therefore, the evidence of a chemical reaction in this scenario is the formation of a precipitate.