Nickel(II) selenate

Identifiers
CAS Number	15060-62-5 anhydrous Y 10101-99-2 hexahydrate Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.035.554
EC Number	239-125-2
CompTox Dashboard (EPA)	DTXSID10934009
SMILES [Ni+2].[O-]Se(=O)(=O)[O-]
Properties
Chemical formula	NiSeO4
Molar mass	201.64
Appearance	green solid[1]
Density	4.8 g·cm−3[2] 2.314 g·cm−3 (hexahydrate)[3]
Related compounds
Other anions	nickel(II) sulfate
Other cations	iron(II) selenate cobalt(II) selenate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Nickel(II) selenate is a selenate of nickel with the chemical formula NiSeO₄.

Preparation

Nickel(II) selenate can be produced by the reaction of nickel(II) carbonate and selenic acid.^[4]

${\displaystyle \mathrm {NiCO_{3}\ +H_{2}SeO_{4}\rightarrow NiSeO_{4}+H_{2}O+CO_{2}\uparrow } }$

Properties

Nickel(II) selenate hexahydrate is a green solid.^[1] It is tetragonal, space group P4₁2₁2 (No. 92).^[5] At 100 °C, nickel(II) selenate hexahydrate slowly loses water to the tetrahydrate, with space group P2₁/n (No. 14). At 510 °C, nickel(II) selenate decomposes directly into nickel selenite, which on further heating decomposes into nickel oxide and selenium dioxide.^[6][2]

${\displaystyle \mathrm {NiSeO_{4}\cdot 6H_{2}O\ {\xrightarrow[{-H_{2}O}]{100\,^{\circ }C))\ NiSeO_{4}\cdot 4H_{2}O\ {\xrightarrow[{-H_{2}O}]{300\,^{\circ }C))\ NiSeO_{4}\cdot H_{2}O\ {\xrightarrow[{-H_{2}O}]{390\,^{\circ }C))\ NiSeO_{4}\ {\xrightarrow[{-O_{2))]{510\,^{\circ }C))\ NiSeO_{3}\ {\xrightarrow[{-SeO_{2))]{690\,^{\circ }C))\ NiO} }$

It and potassium selenate are cooled and crystallized in hot aqueous solution to obtain the blue-green [Ni(H₂O)₆](SeO₄)₂.^[7]

${\displaystyle \mathrm {K_{2}SeO_{4}\ +NiSeO_{4}+6H_{2}O\rightarrow K_{2}[Ni(H_{2}O)_{6}](SeO_{4})_{2)) }$