Advertisements
Advertisements
Question
Why a solution of [Ni(H2O)6]2+ is green while a solution of [Ni(CN)4]2− is colourless? (At. no. of Ni = 28)
Advertisements
Solution
Ni has a valence shell electronic structure of 3d and is in the +2 oxidation state in both compounds. Two unpaired electrons do not couple up when weak-field water ligands are present. Due to the d-d transition, the [Ni(H2O)]2+ possesses two unpaired electrons, giving it a green hue.
The unpaired electrons in the third orbital pair up when a strong field cyanide ligand is present. The [Ni(CN)4]2 is colorless because there are no d-d transitions feasible because there are no unpaired electrons present.
APPEARS IN
RELATED QUESTIONS
Which of the following complexes will give a white precipitate on treatment with a solution of barium nitrate?
- [Cr(NH3)4SO4] Cl
- [Co(NH3)4Cl2] NO2
- [Cr(NH3)4Cl2]SO4
- [CrCl2(H2O)4]Cl
On adding NaOH to ammonium sulphate, a colourless gas with pungent odour is evolved, which forms a blue-coloured complex with Cu2+ ion. Identify the gas.
Aqueous copper sulphate solution (blue in colour) gives a green precipitate with aqueous potassium fluoride. Explain this experimental result.
A solution of [Ni(H2O)6]2+ is green but a solution of [Ni(CN)4]2− is colourless. Explain.
[Fe(CN)6]4− and [Fe(H2O)6]2+ are of different colours in dilute solutions. Why?
What will be the correct order for the wavelengths of absorption in the visible region for the following?
[Ni(NO2)6]4−, [Ni(NH3)6]2+, [Ni(H2O)6]2+
Which of the following is the most likely structure of CrCl3.6H2O if `1/3` of total chlorine of the compound is precipitated by adding AgNO3 to its aqueous solution?
Which of the following complex will give a white precipitate with barium chloride solution?
A solution of [Ni(H2O)6]2+ is green, but a solution of [Ni(CO)4] is colourless. Explain.
[Atomic number: Ni = 28]
Aqueous copper sulphate solution (blue in colour) gives a bright green solution with aqueous potassium chloride. Explain this experimental result.
