Chemistry - Ionic Equilibrium Question with Solution | TestHub
Halides like I⁻, Br⁻, and Cl⁻ are precipitated in the form of AgI, AgBr, and AgCl, respectively. These halides are precipitated successively; that is, when Ag⁺ ions are added to a solution containing, for example, Cl⁻, Br⁻, and I⁻ ions, the least soluble silver salt precipitates first. Precipitation of other halides does not begin until the already precipitating halide has completely precipitated.
To determine the composition of a mixture of halides containing MBr₂ and NaI, a 14 gm mixture was dissolved in water. To this solution, an AgNO₃ solution of a certain molarity was added gradually. The mass of the precipitate produced (in gm) was measured and plotted against the volume of AgNO₃ solution added (in ml), as shown in the diagram.
Select the correct option :
Options:
Answer:
Solution:
The text specifies that for a mixture of halides, the least soluble silver salt precipitates first. Comparing the solubility products (), AgI () is much less soluble than AgBr ().
The graph shows a distinct "break" at 40 mL of AgNO₃, indicating the completion of the first halide's precipitation before the second begins. Since AgI is the least soluble, it must be the first to form, corresponding to the initial 9.4 gm of precipitate.
Therefore, the correct option is (A) AgI starts precipitation first.