Nickel(II) carbonate describes one or a mixture of
inorganic compounds containing
nickel and
carbonate. From the industrial perspective, the most important nickel carbonate is basic nickel carbonate with the formula Ni
4CO
3(OH)
6(H
2O)
4. Simpler carbonates, ones more likely encountered in the laboratory, are NiCO
3 and its hexahydrate. All are
paramagnetic green solids containing Ni
2+ cations. The basic carbonate is an intermediate in the
hydrometallurgical purification of nickel from its ores and is used in electroplating of nickel.
Structure and reactions
NiCO
3 adopts a structure like
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
, consisting of nickel in an
octahedral coordination geometry.
Nickel carbonates are
hydrolyzed
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolysis ...
upon contact with aqueous acids to give solutions containing the ion
i(H2O)6sup>2+, liberating water and
carbon dioxide in the process. Calcining (heating to drive off CO
2 and water) of these carbonates gives
nickel oxide:
:NiCO
3 → NiO + CO
2
The nature of the resulting oxide depends on the nature of the precursor. The oxide obtained from the basic carbonate is often most useful for
catalysis.
Basic nickel carbonate can be made by treating solutions of
nickel sulfate
Nickel(II) sulfate, or just nickel sulfate, usually refers to the inorganic compound with the formula NiSO4(H2O)6. This highly soluble blue green coloured salt is a common source of the Ni2+ ion for electroplating.
Approximately 40,000 tonnes ...
with
sodium carbonate
Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
:
:4 Ni
2+ + CO
32− + 6 OH
− + 4 H
2O → Ni
4CO
3(OH)
6(H
2O)
4
The hydrated carbonate has been prepared by electrolytic oxidation of nickel in the presence of carbon dioxide:
:Ni + O + CO
2 + 6 H
2O → NiCO
3(H
2O)
4
Uses
Nickel carbonates are used in some ceramic applications and as precursors to
catalysts.
Natural occurrence
The natural nickel carbonate is known as
gaspéite - a rare mineral. Basic Ni carbonates also have some natural representatives.
Safety
It is moderately toxic and causes low irritation. Avoid prolonged contact.
References
{{Nickel compounds
Carbonates
Nickel compounds
IARC Group 1 carcinogens