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please help. Thanks In this step, you start with three drops each of solutions o

ID: 953795 • Letter: P

Question

please help. Thanks In this step, you start with three drops each of solutions of Group III cations: Fe^3+, Co^2+, Ni^2+ and Mn^2+. You add concentrated ammonia to make the solution basic, resulting in a precipitate; and then you add (NH_4)_2S, resulting in another precipitate. What are the precipitates formed from the react in between NH_3(aq) and each of the Group III cations? What are the precipitates formed from the reaction between (NH_4)_2S(aq) and each of the Group III cations? Write balanced chemical equations for the reactions forming these two sets of precipitates from each of the four Group III cations. You should have eight chemical equations total.

Explanation / Answer

Qualitative analysis of Group-III cations

a. Addition of NH3 produced precipitates of Fe3+ and Ni2+

b. Addition of (NH4)2S yields precipitates of all the metals, Co2+, Ni2+, Fe3+ and Mn2+

c. Reaction with NH3

Ni2+ + 6NH3 ---> Ni(NH3)6^2+

Fe3+ + 3NH3 + 3H2O ---> Fe(OH)3 + 3NH4+

Reaction with (NH4)2S

Co^2+ + S^2- ---> CoS

2Fe^3+ + 3S^2- ---> Fe2S3

Ni^2+ + S^2- ---> NiS

Mn^2+ + S^2- ---> MnS