Lithium perchlorate

Crystal structure
__ Li +      __ Cl 7+      __ O 2−
Crystal system	orthorhombic
Space group	Pnma (No. 62)
Lattice parameters	a = 8.657 Å, b = 6.912 Å, c = 4.832 Å
General
Surname	Lithium perchlorate
other names	Perchloric acid lithium
Ratio formula	LiClO 4
Brief description	white solid
External identifiers / databases
CAS number 7791-03-9 13453-78-6 (trihydrate) EC number 232-237-2 ECHA InfoCard 100.029.307 PubChem 23665649 ChemSpider 133514 Wikidata Q412015
properties
Molar mass	106.39 g mol −1
Physical state	firmly
density	2.43 g cm −3 1.841 g cm −3 (trihydrate)
Melting point	236 ° C
boiling point	Decomposes at 400 ° C
solubility	soluble in water and ethanol readily soluble in DMSO (315 g l −1 at 25 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-315-319-335 P: 220-261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Lithium perchlorate is the lithium salt of perchloric acid and, like many perchlorates, is a strong oxidizing agent at high temperatures . It is a colorless solid, easily soluble in water, alcohols and some other solvents.

Manufacturing

Lithium perchlorate can be made from perchloric acid and lithium carbonate .

${\displaystyle {\ce {Li2CO3 + 2HClO4 -> 2LiClO4 + H2O + CO2 ^}}}$

properties

Lithium perchlorate crystallizes as the trihydrate LiClO ₄  · 3 H ₂ O in the hexagonal crystal system in the space group P 6 ₃ mc (space group no. 186) . The lattice parameters are a = 7.719  Å and c = 5.455 Å. At 98-100 ° C, it changes into a monohydrate LiClO ₄  · H ₂ O with elimination of water . The anhydrate is formed at 130 - 150 ° C, it is hygroscopic and crystallizes in the orthorhombic crystal system in the space group space group Pnma (space group no. 62) and the lattice parameters a = 8.657 Å, b = 6.912 Å and c = 4.832 Å. In the unit cell contains four formula units .

Lithium perchlorate is soluble to very well in water and polar organic solvents.

Solubility in various solvents at 25 ° C
solvent		water	Methanol	Ethanol	n-propanol	acetone	Ethyl acetate	Diethyl ether
solubility	in g / 100 g solvent	59.71	182.25	151.76	105.00	136.52	95.12	113.72

At 380 ° C, pure lithium perchlorate first decomposes into lithium chlorate , lithium chloride and oxygen. The lithium chlorate formed decomposes in a subsequent reaction into lithium chloride and oxygen:

${\displaystyle {\ce {2LiClO_4 ->[\Delta] LiClO3 + LiCl + O2 ^}}}$

${\displaystyle {\ce {2LiClO_3 \ ->[\Delta] 2LiCl + 3O2 ^}}}$

The overall reaction is therefore:

${\displaystyle {\ce {LiClO4 ->[\Delta] LiCl + 2O2 ^}}}$

Contaminated lithium perchlorate can decompose in a violent reaction below 300 ° C.

handling

Heat, open flames, strong reducing agents and flammable substances should be avoided due to the risk of explosion.

Areas of application

Lithium perchlorate is only used to a limited extent technically because it is expensive and difficult to handle. Since it is relatively soluble in many organic solvents, including ethanol and ether , it is used as an electrolyte , with its application in lithium batteries being particularly important. Another example of its use as an electrolyte in non-aqueous solutions is the production of polypyrrole , which can then also be doped with lithium perchlorate.

Since lithium perchlorate in all previously known perchlorates having the lowest mass-to-volume ratio of oxygen, it is in the air and space travel estimated as an oxygen carrier.

Individual evidence

1. ↑ ^{a b c} M. S. Wickleder: Crystal Structure of LiClO ₄ in Zeitschrift für inorganic und Allgemeine Chemie , 2003 , 629 (9), pp. 1466-1468. doi : 10.1002 / zaac.200300114 .
2. ↑ ^{a b c d e} data sheet Lithium perchlorate, anhydrous at AlfaAesar, accessed on December 15, 2010 ( PDF )(JavaScript required) .
3. ↑ Data sheet Lithium perchlorate trihydrate (PDF) from Strem, accessed on May 14, 2017.
4. ↑ Entry on lithium perchlorate. In: Römpp Online . Georg Thieme Verlag, accessed on July 15, 2014.
5. ↑ Dimethyl Sulfoxide (DMSO) Solubility Data. Gaylord Chemical Company, LLC; Bulletin 102, June 2014, p. 14. (PDF)
6. ↑ ^{a b} data sheet Lithium perchlorate from Sigma-Aldrich , accessed on October 22, 2016 ( PDF ).
7. ↑ ^{a b c} R. Abegg, F. Auerbach, I. Koppel: Handbook of inorganic chemistry . Verlag S. Hirzel, 1908, 2nd volume, 1st part, p. 137. Full text
8. ^ A. Sequeira, I. Bernal, ID Brown, R. Faggiani: "The Structure of Lithium Perhclorate Trihydrate Li (H ₂ O) ₃ ClO ₄ - an X-ray and Neutron Diffraction Study" in Acta Cryst. 1975 , B31 , p. 1735. doi : 10.1107 / S0567740875006000 .
9. ↑ ^{a b} Long, JR: Perchlorate safety: Reconciling inorganic and organic guidelines in Chem. Health Safety 9 (2002) 12-18, doi : 10.1016 / S1074-9098 (02) 00294-0 .
10. ↑ Willard, HH; Smith, GF: The Perchlorates of the Alkali and Alkaline Earth Metals and Ammonium. Their Solubility in Water and Other Solvents in J. Am. Chem. Soc. 45 (1923) 286-297, doi : 10.1021 / ja01655a004 .