Question

Most sulfide compounds of the transition metals are insoluble in water. Many of these metal sulfides have striking and characteristic colors by which we can identify them. Therefore, in the analysis of mixtures of metal ions, it is very common to precipitate the metal ions by using dihydrogen sulfate (commonly called hydrogen sulfide), H2S. Suppose you had a mixture of Fe2+, Cr3+, and Ni2+. Complete the net ionic equations for the precipitation of these metal ions by the use of H2S. (Type your answers using the format Fe2+ for Fe2+.)

Answer 1

See explanation

Step-by-step explanation:

For Fe;

Fe2+(aq) + 2H+(aq) + S2-(aq) ----> FeS(s) + H2(g)

For Ni

Ni2+(aq) + 2H+(aq) + S2-(aq) ----> NiS(s) + H2(g)

For Cr

2Cr3+(aq) + 6H+(aq) + 3S2-(aq) ----->Cr2S3(s) + 3H2(g)

We must remember that in writing these equations, the number of electrons lost or gained must be balanced. The number of electrons lost by the metal must equal the number of electrons gained by hydrogen. This rule was followed in writing all the equations above.