Question

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

• A. < 1
• B. 2 - 3
• C. 3 - 4
• D. 9 - 11

Answer 1

Answer: (D)

9 - 11

Answer 2

Nickel ions $\left( Ni ^{2+}\right)$ can be best estimated qualitatively and quantitatively by the use of dimethylglyoxine (DMG) solution. The reaction occurs as follows : undefined It may be evidently seen that in this reaction each DMG ion lose one proton. Hence, a basic medium is needed to facilitate this reaction. Thus this reaction is carried out in ammoniacal solution $( pH =9-11)$