Dimethyl glyoxime gives a red precipitate with `Ni^(2+)`, which is used for its detection. To get this precipitate readily the best `pH` range is

Options

A. `lt1`
B. `2-3`
C. `3-4`
D. `9-11`

Answer

D

Explanation

Nickel(II) Forms a precipitate with the organic compound dimethyglyoxime,`C_(4)H_(6)(NOH)_(2)`.The formation of the red chelate occurs quantitatively in a solution in which the pH is buffered in the range of 5 to 9 .The chelation reaction that occurs is illustrated below. Although the does loss of one proton occurs from one oxime group(NOH) on each of two molecules of dimethyglyoxime,the chelation reaction occurs due to donation of the electron pairs on the oxygen atoms.The reaction is not by electrons on the oxygen atoms.The reaction is performed in a solution buffered by either an ammonia or citrate buffer to prevent the pH do-es become too low the equillibrium of the above reaction favors the formation of nickel(II) ion,causing the dissolution of `Ni(DMG)_(2)` back into the mother liquor.