Question

Imagine that A and B are cations and X, Y, and Z are anions, and that the following reactions occur: AX(aq)+BY(aq)→no precipitate, AX(aq)+BZ(aq)→precipitate. Which of the following choices is insoluble? a. AX AY b. AZ BX c. BY BZ

Answer 1

Answer: The insoluble substance will be AZ and BY

Explanation:

Precipitation reaction is defined as the reaction in which an insoluble salt is formed when two solutions are mixed containing soluble substances. The insoluble salt settles down at the bottom of the reaction mixture.

Double displacement reaction is defined as the reaction in which exchange of ions takes place.

$AB+CD\rightarrow CB+AD$

For a reaction to form precipitate, the ions must be exchanged in the reaction.

For the given chemical equations:

$AX(aq.)+BY(aq.)\rightarrow \text{No precipitate}$

No exchange of ions took place in the above reaction.

$AX(aq.)+BZ(aq.)\rightarrow \text{Precipitate}$

As, precipitate is forming in the above reaction, the exchange of ions took place.

The reaction now becomes:

$AX(aq.)+BZ(aq.)\rightarrow AZ+BY$

Hence, the insoluble substance will be AZ and BY

Answer 2

Answer:

b. AZ BX

Explanation:

A⁺, B⁺, X⁻, Y⁻ and Z⁻

AX(aq)+BY(aq)→no precipitate

AX(aq)+BZ(aq)→precipitate.

AX(aq)+BY(aq)→no precipitate:

A⁺ (aq) + X⁻ (aq) + B⁺ (aq) + Y⁻ (aq) → AY (aq) + BX (aq)

AX(aq)+BZ(aq)→precipitate:

A⁺ (aq) + X⁻ (aq) + B⁺ (aq) + Z⁻ (aq) → AZ (s) + BX (aq)

Considering the reactions above, the insoluble specie is AZ.