Question

POST LAB QUESTIONS Answer the following questions in your lab notebook: 1. Give the chemical formula for a single chemical reagent that would : (a) separate Ag from Cut b) separate AgCl from PbCl2 - separate Cu2+ from Mat (d) separate Fet from Zn2+ (e) Dissolve Zn(OH), but not Fe(OH)3 (f) separate Ba2+ from Mn2+ and Zn2+ 2. Write balanced ionic chemical equations for: a. The dissolution of AgCl in excess ammonia b. The precipitation of Pb * to PbCrO4(s) c. The hydrolysis of thioacetamide (CH3CSNH) at high temperature to yield H2S gas. - The precipitation of Cut by #1,5 in acidic medium. e. The complex formation of Cu* in ammonia solution f. The complex formation of Fe" in KSCN solution. g. The oxidation of Mnto MnO, using NaBiO; solution in acidic medium. h. Write two ionic equations to illustrate the amphoteric nature of Zn(OH)2. i. The confirmation test for NHA j. The confirmation test for Bat not the flame test.) 3. Write the step-wise net ionic equations for all the cations that show amphoteric behavior in excess NaOH solution (include Al" ion although it was not tested in the lab.) 4. Write the balanced net ionic equations for all the cations which exhibit complex formation with ammonia. (include Nic and Co" although they were not tested in the lab.)

Answer 1

a) dil HCl; forms a white precipitate of silver chloride

b) hot water; In hot water, PbCl2 will dissolve while AgCl remains insoluble

c) H2S in acidic media; black ppt of CuS is formed.

d) 6 M NaOH. A dark precipitate forms will confirm the presence of Fe3+

e)  excess NaOH, zinc hydroxide will form a colorless solution of zincate ion: Zn(OH)₂ + 2 OH− → Zn(OH)₄^2-

whereas ferric Hydroxide will not.

f) 3M Sulphuric acid; barium ions forms white precipitate of barium sulphate.