Report for Experiment 3-Chemistry 104 B. Multi-ion mixtures SAMPLE# 76 Mixture o
ID: 950078 • Letter: R
Question
Report for Experiment 3-Chemistry 104 B. Multi-ion mixtures SAMPLE# 76 Mixture of unknown - metal ions Colorless ,6"82. Add about 10 drops of 6M HC Put in ice bath about 2 min -Centrituge about i min: Decant Wash ppt white pt colodess Add abo 20 drops H,O, shake dd about 10 drops of GM NHq) unti about 5-7 min: Centrifuge about 1 min. Decant mmers in boting water bah basic (red semus paper tuins bue Centrifuge about 1 min Decant, nte r AgCl solid Wash ppt Mixture of Ni . Ba Fe (OH) Dissolve solids in HrIO,. 1 drop at a time until totally dissolved liquid Add about 8-10 drops K,CIO Centiituge about 1 min D E Pb- Decant Fe Liquid tested wth k5cN yellom buhite Pet Liquid tested wtlh Hci Results of test No Renition Results of test No Renctien Student Flowchart for question B1.Explanation / Answer
a) Ag+ The student is right . With Hcl siver forms AgCl as white precipitate which is insoluble in boiling water.
b) Pb+2 Possibly. Instead of KSCN, lead is tested better with either KI or K2CrO4 which gives yellow precipitate of lead iodide /lead chromate.
c) Fe+3 . No Ferric hydroxide is reddish brown in colour not white. He is wrong. He possibly has precipitated barium hydroxide. Nickel hydroxide is green in color.
To test for Fe, NH4Cl +ammonia are added so that only Fe+3, Al+3 or Cr+3 are precipitated not only ammonia.
d) Ba+2 possibly correct.
barium with potassium chromate gives yellow precipitate of barium chromate which is insoluble in acetic acid.
e) Ni+2 Wrong.
when nickel is treated with HCl, it forms soluble nickel chloride , hence it may be missed.
Instead Ni+2 can be tested by using ammonia+H2S or ammonia + dimethylglyoxime which give blackprecipitate and blood red coloration respectively.