- Fluoride Ion Apparently Fluoride And Chromium Chromium Iii Makes Stable Complexes With Fluoride Ions Log K 4 36 3 1 (33.27 KiB) Viewed 47 times
fluoride ion apparently Fluoride and Chromium Chromium(III) makes stable complexes with fluoride ions (log K₁ = 4.36, 3.36, 2.48, for n= 1, 2, 3, respectively) When 150 ml. 22 M ammonium fluoride solution is dropwise added to 200 mL SM chromium(III)nitrate-solution a grey-violet solid salt ([Cr(H20)6] Fa) is precipitated. A solution of the salt gives an absorption spectrum with a first maximum at λ = 575mm. However, the spectrum changes with time as the counter ions gradually substitute the water molecules 3) (6) Discuss whether the positon of the absorption maximum will gradually change to higher or lower wavelengths, Comment your answer. The grey-violet salt reacts with excess of pyridine (and heating) giving the intermediate product (CrFa(py)s) (py pyridine) Further reaction with amines results in the complex [CrFs(NH)x] 4) (9) At what wavelength can the first absorption maximum be expected for the product [CrFi(NH)], when it is observed that the hexafluorochromate(III)-ion ([CrF6]3-) gives absorption at 661 nm, and that the corresponding hexaamminechromate(III) ion ([Cr(NH₂)) gives absorption maximum at 465 nm?