Nickel

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Other names/abbreviations:

Ni

Element no:	28
Element group:	10 (IUPAC) VIII B (American labelling) VIII A (European labelling)
Element type:	Transition metals
CAS-Number:	7440-02-0
EINECS-Number:	231-111-4

Chemical properties

Reaction of nickel with acids
Nickel metal dissolves slowly in dilute sulphuric acid to form the aquated Ni(II) ion and hydrogen, H₂. In aqueous solution, Ni(II) is present as the complex ion [Ni(H₂O)₆]²⁺.

Ni (s) + H₂SO₄ (aq) Ni²⁺ (aq) + SO₄^2- (aq) + H₂ (g)

The strongly oxidizing concentrated nitric acid, HNO₃, reacts on the surface of iron and passivates the surface.


Reaction of nickel with ammonia
Nickel(II)-ions are precipitated by ammonia as a green gelatinous precipitate of nickel(II)hydroxide which dissolves forming a deep blue hexaaminenickel(II) hydroxide at excess ammonia [4]

Ni²⁺ (aq) + 2 OH^- (aq) 2 Ni(OH)₂ (s) [light green]
Ni(OH)₂ (s) + 6 NH₃ (aq) [Ni(NH₃)₆]²⁺ (aq) + 2 OH^- (aq) [deep blue]


Reaction of nickel with halogens
Nickel reacts slowly with halogens, forming the corresponding dihalides.

Ni (s) + Cl₂ (g) NiCl₂ (s) [yellow]
Ni (s) + Br₂ (g) NiBr₂ (s) [yellow]
Ni (s) + I₂ (g) NiI₂ (s) [black]

Nickel(II) can be oxidized to nickel(III) using Br₂ under alkaline conditions

2 Ni(OH)₂ (s) + Br₂ (aq) + 2 OH^- (aq) 2 Ni(OH)₃ (s) + 2 Br^- (aq)


Reaction of nickel with hydroxide ions
Metallic nickel does not react with aqueous sodium hydroxide [4].

Nickel(II)-ions are precipitated by hydroxide ions forming a green gelatinous precipitate [4]

Ni²⁺ (aq) + 2 OH^- (aq) 2 Ni(OH)₂ (s) [light green]


Reaction of nickel with sulfide
Nickel(II)-ions are precipitated by sulfide either using H₂S and acetic acid (HCl can't be used) or Na₂S under neutral to alkaline conditions forming the black NiS

Ni²⁺ (aq) + S^2- (aq) NiS (s) [black]


Reaction of nickel with water
Nickel metal does not react with water under normal conditions.

Nickel(II)-ions complexes with water under acidic and neutral conditions forming a light green hexaqua nickel ion [4].

Quantitative analysis

Method 3500-Ni C Inductively Coupled Plasma Method [2]. A portion of the sample is digested in a combination of acids. The digest is aspirated into an 8,000 K argon plasma where resulting light emission is quantified for 30 elements simultaneously.

Method limit of detection in water = 0.005 mg/L
Method limit of detection in soil = 1.00 mg/kg

Safety

Symbol: Xn
R-phrases: 40-43
S-phrases: 22-36

Physical properties

Appearance
	Physical state @ 20°C:	Solid [5]
	Color:	Gray [5]
	Odor:	Odourless [5]

Bulk properties
	Molecular weight (g/mol):	58.6934(2) [1]
	Melting point (°C):	1455 [1]
	Boiling point (°C):	2920 [1]
	Density (g/cm3):	8.908 [1]
	Molar volume (cm3):	6.64 (20 °C) [3]
	Elastic properties: Youngs modulus (GPa): Rigidity modulus (GPa): Bulk modulus (GPa): Poissons ratio	197-200 [3] 76 [3] 177 [3] 0.31-0.36 [3]

Thermodynamic properties
	ΔfH°gas (kJ/mol):	429±13 (monoatomic) [1] 429.7 [6]
	ΔfH°solid (kJ/mol):	0.0 [6]
	ΔH°fusion (kJ/mol):	17.48 [6]
	ΔH°vaporization (kJ/mol):	375±17 [1]
	S°gas (J/K·mol):	182.2 [6]
	S°solid (J/K·mol):	29.9 [6]
	ΔfG°gas (kJ/mol):	384.5 [6]
	Cp (gas) (J/K·mol):	23.4 (25 °C) [6]
	Cp (solid) (J/K·mol):	25.303 (20 °C) [3] 26.07 (25 °C) [6] 27.759 (100 °C) [3] 30.953 (200 °C) [3] 33.656 (300 °C) [3] 34.884 (900 °C) [3]
	Coeff. of linear thermal expansion (106 K-1):	13.3 (20 °C) [3] 13.4 (25 °C) [6] 13.3 (100 °C) [3] 13.9 (200 °C) [3] 14.4 (300 °C) [3] 16.3 (900 °C) [3]

Crystal structure
	Crystal type:	Face centered cubic [3]

Electronic properties
	Electron configuration:	1s2-2s2-2p6-3s2-3p6-3d8-4s2
	Ionic radius (Å):	Ni(IV): 0.48 (6-coordinate) [1] Ni(III): 0.56 (6-coordinate, low-spin) [1] Ni(III): 0.60 (6-coordinate, high-spin) [1] Ni(II): 0.69 (6-coordinate) [1]

Conductivity
	Electrical resisitvity (μΩ·cm):	6.90 (20 °C) [3] 6.20 (25 °C) [3] 10.3 (100 °C) [3] 15.8 (200 °C) [3] 22.5 (300 °C) [3] 45.5 (900 °C) [3]
	Thermal (W/m·K):	88.0 (20 °C) [3] 90.7 (27 °C) [6] 82.9 (100 °C) [3] 73.3 (200 °C) [3] 63.6 (300 °C) [3]

History

Origin of name
From the German word "kupfernickel" meaning copper (kupfer) and devil (nickel). In the seventeents century nickel ores were mistaken for copper ores beause of the similarity in appearance. Kupfernickel refers to the belief that a devil prevented the extraction of copper from these ores [4].

References

1: Greenwood,N.N., Earnshaw,A. Chemistry of the elements
2nd edition (1997) Edited by Greenwood,N.N., Earnshaw,A. pp. 1-1340, Butterworth-Heinemann. Oxford. Great Britain

2: Standard Methods for the Analysis of Water and Wastewater, APHA, 1992, 18th edition

3: Pure Metals Properties. A Scientific-Technical Handbook
1st edition (1999) Edited by Buch,A. pp. 1-306, ASM International and Freund Publishing House Ltd. Ohio. USA

4: General chemistry
7th edition (1984) Edited by Holtzclaw, Jr.,H.F., Robinson,W.R. & Nebergall,W.H. pp. 1-932. D.C. Heath and Company. Lexington

5: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5

6: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA

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© Michael Pilgaard
Created: October 3, 2008
Last update: October 9, 2008