When a mixture containing cations of Analytical Groups I–III is treated with H2S in acidic solution, which cations are expected to precipitate? Analytical Groups I and II Analytical Group I only Analytical Group III only Analytical Groups II and III Analytical Group II only

Analytical Groups I and II

Explanation:

Precipitation reactions happen when anions and cations in aqueous solution mix together to form an insoluble ionic solid which is now referred to as a precipitate.

Whether or not a type of reaction like that takes place can be determined by utilizing the solubility principles for common ionic solids.

Option D is the answer :

Analytical Groups II and III

Explanation:

Group II (Cu2+, Bi3+, Cd2+, Hg2+, As3+, Sb3+, Sn4+) cations produce very insoluble sulfides

(Ksp values less than 10-30) so they can be precipitated by low amounts of sulfide ion; this can be

achieved by adding an acidic solution of H2S.

Group III (Al3+, Cr3+, Fe3+, Zn2+, Ni2+, Co2+, Mn2+) cations produce slightly soluble sulfides

(Ksp values more than 10-20) so they can be precipitated by relatively high amounts of sulfide ion;

this can be achieved by adding a basic solution of H2S