Why is H2 more stable than LiH



Lithium hydride LiH is a salt-like chemical compound of lithium and hydrogen. As it is very light and stable, it is an excellent hydrogen storage device with a capacity of 2.7 m3 H2/ kg LiH. The hydrogen can be released by reaction with water.

Occurrence

Since lithium hydride is highly reactive, it is made exclusively synthetically from lithium. Important lithium minerals are spodumene LiAlSi2O6 and lepidolite (lithium mica) a lithium aluminum silicate containing potassium and fluorine.

Extraction and presentation

After digestion of the minerals with sulfuric acid, lithium is precipitated as lithium carbonate with sodium carbonate. The metal is obtained electrolytically from a lithium chloride / potassium chloride melt or a lithium chloride solution in pyridine. Finally, lithium hydride is produced by reacting metallic lithium with hydrogen at 600–700 ° C.

properties

Physical Properties

Lithium hydride is a white to gray, flammable powder with a density of 0.76 g / cm3 is one of the lightest solids. It melts at 680 ° C and boils at 800-850 ° C (with decomposition).[2]

Chemical properties

Lithium hydride is flammable:[1]

It reacts with water, acids and bases:

It reduces or hydrogenates organic compounds, for example formaldehyde (methanal) to methanol:

use

Lithium hydride is used as a reducing / hydrogenating agent (hydrogen donor) for the production of hydrides and double hydrides.[2] It is also used to deprotonate C, H-acidic compounds. Another area of ​​application is the production of the hydrogenating agents lithium boranate and lithium alanate.

Lithium deuteride is used as fuel in hydrogen bombs. Here the ordinary hydrogen (protium) has been replaced by the heavy hydrogen isotope deuterium.

credentials

  1. abcdefGH Entry to Lithium hydride in the GESTIS substance database of the BGIA, accessed on November 8, 2007 (JavaScript required)
  2. ab Properties of lithium hydride

Categories: Flammable Substance | Corrosive substance | Lithium compound | Nuclear material | Hydride