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When 0.10 M aqueous solutions are combined, which of these pairs forms a precipitate?

a) NH₄NO₃ + Pb(NO₃)₂
b) NaNO₃ + KCl
c) HNO₃ + Ca(OH)₂
d) Pb(C₂H3O₂)₂ + NH₄Cl

1 Answer

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Final answer:

Out of the given options, option (d) Pb(C2H3O2)2 + NH4Cl will form a precipitate. When lead (II) reacts with a chloride, as in the reaction of Pb(NO3)2 with KI forming PbI2, it results in the formation of an insoluble salt, which in this case will be lead (II) chloride (PbCl2).

Step-by-step explanation:

When combining 0.10 M aqueous solutions to determine which pair forms a precipitate, one should refer to the solubility rules. In this case, option (a) NH₄NO₃ + Pb(NO₃)₂ does not form a precipitate because all nitrates are soluble. Option (b) NaNO₃ + KCl also doesn't lead to a precipitate because nitrates and chlorides (except those of Ag+, Pb2+, and Hg₂2+) are soluble.

Option (c) HNO₃ + Ca(OH)₂ does not form a precipitate as nitrates are soluble and Ca(OH)₂ is soluble in the presence of strong acids like HNO₃. Lastly, option (d) Pb(C₂H3O₂)₂ + NH₄Cl will result in a precipitate. According to the solutions provided, when Pb(NO₃)₂ reacts with KI, a precipitate of PbI₂ forms. By analogy, replacing KI with NH₄Cl in option (d), where the lead (II) compound reacts with a chloride, a similar reaction will occur, forming PbCl₂ as a precipitate.

User Boris Strandjev
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