Sodium
Main page |
| Other names/abbreviations: | Na Natrium |
| Element no: | 11 |
| Element group: | 1 (IUPAC) I A (American labelling) I A (European labelling) Alkali metals |
| Element type: | Metals |
| CAS-Number: | 7440-23-5 |
| EINECS-Number: | 231-132-9 |
Safety
Symbol: F, CR-phrases: 14/15-34
S-phrases: 5-8-43-45
Quantitative analysis
Method 3500-Na 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 = 1.0 mg/L
Method limit of detection in soil = 100.0 mg/kg
Physical properties
Appearance | ||
| Physical state @ 20°C: | Solid [4] | |
| Color: | Silver gray [4] | |
| Odor: | Odourless [4] | |
Bulk properties | ||
| Molecular weight (g/mol): | 22.989768(6) [2] | |
| Melting point (°C): | 97.8 [2] | |
| Boiling point (°C): | 883 [2] | |
| Ignition temperature (°C): | > 115 [4] | |
| Density (g/cm3): | 0.97 (20°C) [4] 0.968 [2] | |
| Molar volume (cm3): | 23.70 (20 °C) [3] | |
| Elastic properties: Youngs modulus (GPa): Rigidity modulus (GPa): Bulk modulus (GPa): Poissons ratio |
6.8 [3] 2.53 [3] 5.32 [3] 0.34 [3] | |
| Hardness: Mineral hardness: |
0.4 [3] | |
Thermodynamic properties | ||
| ΔfH°gas (kJ/mol): | 108 (monoatomic) [2,5] 142.1 (Na2) [5] | |
| ΔfH°solid (kJ/mol): | 0.0 [5] | |
| ΔH°fusion (kJ/mol): | 2.64 [2] | |
| ΔH°vaporization (kJ/mol): | 99 [2] | |
| S°gas (J/K·mol): | 153.7 (monoatomic) [5] 230.2 (Na2) [5] | |
| S°solid (J/K·mol): | 51.3 (monoatomic) [5] | |
| ΔfG°gas (kJ/mol): | 77.0 (monoatomic) [5] 103.9 (Na2) [5] | |
| Cp (gas) (J/K·mol): | 20.8 (monoatomic, 25 °C) [5] 37.6 (Na2, 25 °C) [5] | |
| Cp (solid) (J/K·mol): | 28.230 (monoatomic, 25 °C) [5] | |
| Coeff. of linear thermal expansion (106 K-1): | 71 (25 °C) [5] | |
Crystal structure | ||
| Crystal type: | Body centered cubic [3] | |
Electronic properties | ||
 |
Electron configuration: | 1s2-2s2-2p6-3s1 |
| Atomic radius (Å): | 1.86 [6] | |
| Ionic radius (Å): | 1.02 [2] | |
| Electron affinity [M-M-] (kJ/mol): | 52.9 [2] | |
Conductivity | ||
| e°(V): | -2.714 [2] | |
| Electrical resisitvity (μΩ·cm): | 4.70 (20 °C) [3] 4.93 (25 °C) [3] | |
| Thermal (W/m·K): | 141 (27 °C) [5] | |
Occurrence, isolation & synthesis
IsolationOriginally Na was produced by reducing Na2CO3 with C [6]:
Na2CO3 + 2 C
2 Na + 3 CO (g)Currently the process used is electrolysis of melted NaCl [6].
Cathode: Na+ (l) + e-
Na (l)Anode: Cl- (l)
½ Cl2 (g) + e-NaCl melts at 801 °C, so the process is carried out in a mixture of NaCl and CaCl2 or Na2CO3 with a melting point of about 600 °C.
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: 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
4: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5
5: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA
6: 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
© Michael Pilgaard
Created: October 2, 2008