Oxidation states of nickel and reactions with it
Physical and chemical properties of nickel
Nickel is a chemically low-active metal, with a silvery-white color. The element has the symbol Ni and is located in the tenth group of the fourth period in the periodic system.
The name of this element has an interesting origin: Nicolaus, which nickel was named after, was the name of an evil spirit in German mythology, a mischievous, two-faced character. This is because the ore that nickel is extracted from looks very similar to copper, but by its chemical composition is nickel arsenide (red nickel pyrite), which releases poisonous arsenic gases when melted. Attempts to extract copper were unsuccessful, but in 1751 the Swedish mineralogist Cronstedt extracted a green oxide, and by reducing it obtained a metal which was subsequently named nickel.
Nickel in nature
The main nickel ores are:
- nickeline (red nickel pyrite, copper-nickel) NiAs;
- millertie (yellow nickel pyrite) NiS;
- pentladite (Fe,Ni)₉S₈;
- magentic pyrite (Fe, Ni, Cu)S;
- arsenic-nickel glance (gersdorffite) NiAsS.
Application of nickel
Although this element has a low chemical activity, it has found wide application in industry, for example nickel is used to coat other metals to protect them from corrosion. Very fine metal plates can also be made from nickel, which are used in electronics, for example in batteries.
Nickel alloys are also used in prostheses and dental braces.
Physical properties of nickel
Nickel is a metal of a silvery-white color, which does not grow dull. In air, it becomes covered with an oxide film.
In itself nickel is very hard, but at the same time it is quite malleable and ductile.
Melting temperature 1455 °C, boiling temperature around 2900 °C, density 8.90 kg/dm³. Nickel is ferromagnetic, with a Curie point of around 358 °C.
Chemical properties of nickel
Nickel in compounds can have the following oxidation states: +1, +2, +3 and +4. Compounds in which nickel has an oxidation state of +4 are very rare and unstable.
When heated above 800°C it reacts with oxygen, forming nickel oxide:
2Ni + O₂ → 2NiO
Nickel powder ignites spontaneously in air and nickel oxides form:
5Ni + 3O₂ → 3NiO + Ni₂O₃
It interacts with carbon monoxide, forming the poisonous gas carbonyl:
Ni + 4СO → Ni(СO)₄
It interacts with nitrogen at a high temperature, forming nickel nitride:
Ni + N₂ = Ni₃N₂ ?
With sulfur the reaction takes place exothermically:
Ni + S = NiS
When heated, it forms compounds of a non-stoichiometric composition with carbon, boron, silicon and phosphorus, for example:
3Ni + C = Ni₃C,
2Ni + B = Ni₂B,
Ni + Si = NiSi,
3Ni + P = Ni₃P.
The metal reacts with halogens, forming halogenides:
Ni + Cl₂ = NiCl₂.
Nickel can absorb hydrogen, forming solid solutions of hydrogen in nickel.
Metallic nickel reacts with nitric acid:
3Ni + 8HNO₃ = 3Ni(NO₃)₂ + 2NO + 4H₂O
When heated it reacts with concentrated nitric and sulfuric acids:
Ni + 2H₂SO₄ = NiSO₄ + SO₂ + 2H₂O,
Ni + 4HNO₃ = Ni(NO₃)₂ + 2NO₂ + 2H₂O.
With diluted solutions of hydrochloric and sulfuric acid,
Ni + 2HCl = NiCl₂ + H₂,
Ni + H₂SO₄ = NiSO₄ + H₂;
Nickel forces metals out of their salt solutions which are located to the right of it in the electrochemical series:
Ni + CuSO₄ = NiSO₄ + Cu.
Nickel does not interact with water, alkalis or fluorine even when heated.
Here you’ll find amazing experiments for learning properties of different metals.
Reaction for detecting nickel ions
To conduct the qualitative reaction for nickel, Chugaev’s reagent (dimethyl glyoxime) is used. If Chugaev’s reagent is added to an ammonium solution of nickel salt, a sediment of a bright crimson color forms. With this reaction, ions of nickel can be detected. Nickel can even be detected if there is a low content of nickel ions in the solution, in any case the solution turns crimson when the reagent is added.