Question

Write the name of reagent to identify $C{o}^{2+}.$

• A. $N{H}_{4}CNS$
• B. Dimethyl glyoxime in $N{H}_{4}OH$ / alcoholic solution or DMG
• C. $H_{2}S$ gas
• D. None of the above

Answer 1

Answer: (A)

$N{H}_{4}CNS$ is the reagent used to identify $C{o}^{2+}.$ $CoC{l}_2+4N{H}_{4}SCN\to$ $\underset{Bluecolour}{{(N{H}_4)}_2[Co{(SCN)}_4]}+2N{H}_{4}Cl$ $N{H}_{4}CNS$ can be used to make distinction between $C{u}^{2+}$ and $C{o}^{2+}$ . $CuC{l}_2+2N{H}_{4}SCN\to \underset{Blackppt.}{Cu{(SCN)}_2}\downarrow +2N{H}_{4}Cl$