Vanadium
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| Other names/abbreviations: | V Panchromium Erythronium |
| Element no: | 23 |
| Element group: | 5 (IUPAC) V B (American labelling) V A (European labelling) |
| Element type: | Transition metals |
| CAS-Number: | 7440-62-2 |
| EINECS-Number: | 231-171-1 |
Chemical properties
Reaction of vanadium with acidsIn a solution of acetic acid, sodium vanadate forms yellow decavanadate ions: [V10O28]6-, [V10O27(OH)]5-, [V10O22(OH)2]4-. The decavanadate ions exist at 1 > pH > 6.
VO43- (aq) + 25 H+ (aq)
[V10O27(OH)]5- (aq) + 12 H2O (l)In mineral acids at pH ≥ 1, V(V) exist as the pale yellow dioxovanadium ions VO2+.
VO43- (aq) + 4 H+ (aq)
VO2+ (aq) + 2 H2O (l)In cold concentrated hydrochloric acid, red brown chloro complexes are formed.
V(V) is reduced to V(IV) by ascorbic acid. The reaction is fast [3].
Reaction of vanadium with air
Vanadium metal reacts with excess oxygen, O2, upon heating to form vanadium(V) oxide, V2O5. When prepared in this way, V2O5 is sometimes contamined by other vanadium oxides.
4V (s) + 5 O2 (g)
2 V2O5 (s) [yellow-orange]Reaction of vanadium with bases
Vanadium metal is resistant to attack by molten alkali.
In strong alkaline solutions (pH > 13) V(V) exist as colorless orthovanadate ions, VO43-. At lower pH a protonized form is formed VO4(OH)2-, that condensates to pyrovanadate ions (12 > pH >9) [V2O7]4-, [HV2O7]3-, [V2O6(OH)]3-, and metavanadate ions (9 > pH > 6) [VO(OH)3], [VO2(OH)2]-, [V3O9]3-, [V4O12]4-.
Reaction of vanadium with ethanolamines
V(V) is reduced to V(IV) by amines [3].
| Ethanolamines | Reductive coefficient (x 10-6 M-1·s-1) | |
| Monoethanol amine Diethanol amine Triethanol amine |
0.57 1.90 5.01 | |
| Reductive coefficients for ethanolamines adapted from [3]. | ||
Reaction of vanadium with glycols
V(V) is reduced to V(IV) by glycols [3].
| Glycols | Reductive coefficient (x 10-6 M-1·s-1) | |
| Ethylene glycol Diethylene glycol Triethylene glycol Tetraethylene glycol PEG |
119 3.90 4.58 4.38 5.82 | |
| Reductive coefficients for glycols adapted from [3]. | ||
Reaction of vanadium with hydrogen peroxide
Alkaline solution:
VO43- (aq) + HO2- (aq)
[V(O2)O3]3- (aq) [monoperoxovanadate, light yellow] + OH- (aq)Acidic solution:
VO2+ (aq) + H2O2 (aq)
V(O2)O+ (aq) [monoperoxooxovanadium ions, red brown] + H2O (l)In strong acidic solutions the V(O2)O+ ion is parted forming oxovanadium ions, VO2+
V(O2)O+ (aq) + 2 H+ (aq)
VO2+ (aq) [oxovanadium ions, blue] + O2 (g) + H2O2 (aq)Reaction of vanadium with monosaccharides
V(V) is reduced to V(IV) by saccharides under acidic conditions [3].
| Monosaccharide | Reductive coefficient (x 10-5 M-1·s-1) | ||
| Hexoses | D-fructose D-galactose D-glucose |
321 4.72 3.08 | |
| Pentoses | D-ribose D-xylose |
19.1 14.0 | |
| Reductive coefficients for saccharides and derivatives adapted from [3]. | |||
Reaction of vanadium with nucleotides
V(V) is reduced to V(IV) by L-cysteine. Reductive coefficient = 1.08·10-1 M-1·s-1 [3].
Reaction of vanadium with sulfide
V(V) is not precipitates by sulfide in 0.4M HCl, but is reduced to V(IV). Under alkaline conditions:
VO43- (aq) + 4 S2- (aq) + 4 H2O (l)
VS43- (aq) [thiovanadate ions, red] + 8 OH- (aq)VS43- (aq) + 6 H+ (aq)
V2S5 (s) [black/brown] + 3 H2S (aq)Redox reaction of vanadium
V(V) is reduced under acidic conditions to the blue V(IV) (vanadyle ions) by reducing agents like H2S and SO2
VO2+ (aq) + SO2 (aq)
VO2+ (aq) + SO42- (aq)VO2+ (aq) + 2 OH- (aq)
VO(OH)2 (s) [brown]Using strong reduction agents like Zn under acidic conditions reduces V(V) to V(II). During the transition, V(IV) [blue], and V(III) [green] can be observed.
2 VO2+ (aq) + 3 Zn (s) + 8 H+ (aq)
2 V2+ (aq) + 3 Zn2+ (aq) + 4 H2O (l)Solubility
Water: Insoluble (20 °C) [5]
Quantitative analysis
Method 3500-V C Inductively Coupled Plasma Method [1]. 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: -R-phrases: -
S-phrases: -
Physical properties
Appearance | ||
| Physical state @ 20°C: | Solid [5] | |
| Color: | Gray [5] | |
| Odor: | Odourless [5] | |
Bulk properties | ||
| Molecular weight (g/mol): | 50.9415(1) [1] | |
| Melting point (°C): | 1915 [1] | |
| Boiling point (°C): | 3350 [1] | |
| Density (g/cm3): | 6.11 [1] | |
| Molar volume (cm3): | 8.30 (20 °C) [4] | |
| Elastic properties: Young's modulus (GPa): Rigidity modulus (GPa): Bulk modulus (GPa): Poissons ratio: |
124-132 [4] 44-55 [4] 158 [4] 0.36 [4] | |
Thermodynamic properties | ||
| ΔfH°gas (kJ/mol): | 514.2 [6] | |
| ΔfH°solid (kJ/mol): | 0.0 [6] | |
| ΔH°fusion (kJ/mol): | 17.5 [1] 21.50 [6] | |
| ΔH°vaporization (kJ/mol): | 459.7 [1] | |
| S°gas (J/K·mol): | 182.3 [6] | |
| S°solid (J/K·mol): | 28.9 [6] | |
| ΔfG°gas (kJ/mol): | 754.4 [6] | |
| Cp (gas) (J/K·mol): | 26.0 (25 °C) [6] | |
| Cp (solid) (J/K·mol): | 25.159 (20 °C) [4] 24.89 (25 °C) [6] 25.799 (100 °C) [4] 28.997 (500 °C) [4] 30.703 (700 °C) [4] 32.409 (900 °C) [4] | |
| Coeff. of linear thermal expansion (106 K-1): | 8.4 (25 °C) [6] 8.3 (100 °C) [4] 9.6 (500 °C) [4] 10.4 (900 °C) [4] | |
Crystal structure | ||
| Crystal type: | Body centered cubic [4] | |
Electronic properties | ||
 |
Electron configuration: | 1s2-2s2-2p6-3s2-3p6-3d3-4s2 |
| Ionic radius (Å): | V(V): 0.54 (6-coordinate) [1] V(IV): 0.58 (6-coordinate) [1] V(III): 0.64 (6-coordinate) [1] V(II): 0.79 (6-coordinate) [1] | |
Conductivity | ||
| Electrical resisitvity (μΩ·cm): | 24.8 (20 °C) [4] 31.5 (100 °C) [4] | Thermal (W/m·K): | 30.7 (27 °C) [6] 8.3 (100 °C) [4] 9.6 (500 °C) [4] 10.4 (900 °C) [4] |
References
1: Standard Methods for the Analysis of Water and Wastewater, APHA, 1992, 18th edition2: 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
3: Bandwar,R.P., Rao,C.P. Relative reducing abilities in vitro of some hydroxy-containing compounds, including monosaccharides, towards vanadium(V) and molubdenum(VI)
Carbohydr. Res. (1995) 277 197-207
4: Buch,A. 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
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
© Michael Pilgaard
Created: October 7, 2008
Last update: October 12, 2008