Qualitative Cation Tests Essay Example for Free

Qualitative Cation Tests Essay Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor. Observations Questions A. Write net ionic equations for all reactions that produce a precipitate. Ag+(aq.) + Cl-(aq.) -ïÆ'   AgCl (s) 2 Ag+(aq.)+ 2OH- ïÆ'   Ag2O (s) + H2O(l) 2 Ag+(aq.)+2NH3+ H2O(l) ïÆ'   Ag2O (s)+ 2NH4+ (aq.) Pb2+(aq.)+2Cl- (aq.) -ïÆ'   PbCl2(s) Pb2+(aq.)+2OH-(aq.) -ïÆ'  Pb(OH)2 (s) Pb2+(aq.)+ 2NH3(aq.)+ H2O(l) ïÆ'   Pb(OH)2 (s)+ 2NH4+ (aq.) Cu2+(aq.) +2OH-(aq.) -ïÆ'   Cu(OH)2 (s) 2Cu2+(aq.)+SO42- (aq.) +2NH3(aq.)+2 H2O(l) ïÆ'   Cu(OH)2.CuSO4(s) +2NH4+ (aq.) Zn2+ (aq.)+ 2OH- (aq.) -ïÆ'   Zn(OH)2 (s) Zn2+ (aq.)+2NH3(aq.)+ H2O(l) ïÆ'   Ag2O (s)+ 2NH4+ (aq.) Fe3+ (aq.)+ 3OH- (aq.) -ïÆ'   Fe(OH)3(s) Fe3+ (aq.)+ 3NH3(aq.)+ 3H2O(l) ïÆ'   Fe(OH)3(s)+ 3NH4+ (aq.) Pb2+(aq.)+ CrO42-(aq.) PbCrO4(s) 2Cu2+(aq.)+[Fe(CN)6]4- (aq.) ïÆ'  Cu2[Fe(CN)6] (s) Zn2+(aq.) + S2-(aq) ïÆ'   ZnS(s) 4Fe3+ (aq.)+3[Fe(CN)6]4- (aq.) -ïÆ'  Fe4[Fe(CN)6]3 (s) Ca2+(aq) + ( COO)22-(aq) ïÆ'   Ca(COO)2 (s) B. Identify the cations that precipitate with hydrochloric acid and dissolve in the presence of ammonia. Ag+ C. Identify the cations that precipitate with hydrochloric acid and do not redissolve in the presence of ammonia. Pb2+ D. Identify the cations that precipitate upon addition of two or three drops of sodium hydroxide but redissolve upon addition of excess sodium hydroxide. Pb2+,Zn2+ E. Identify the cations that precipitate upon addition of two or three drops of sodium hydroxide and are not affected by additional sodium hydroxide. Ag+,Cu2+,Fe3+ F.Identify the cations that precipitate upon addition of two or three drops of aqueous ammonia but redissolve upon addition of excess aqueous ammonia. Ag+,Cu2+,Zn2+ G. Identify the cations that precipitate upon addition of two or three drops of aqueous ammonia and are not affected additional aqueous ammonia. Pb2+,Fe3+ H. What simple test would distinguish Ag+ and Cu2+ ? Upon addition of two or three drops of aqueous ammonia, Ag+ produces brown ppt, which is soluble in the excess reagent, resulting in clear, colorless solution. Upon addition of two or three drops of aqueous ammonia, Cu2+ produces blue ppt, which is soluble in the excess reagent but produces dark blue solution.