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LiHe

LiHe, also known as lithium hydride, is a chemical compound with the formula LiH. It is a simple ionic compound consisting of lithium (Li) and hydrogen (H) and is notable for being the lightest ionic compound. LiHe is primarily used in various industrial applications, including as a desiccant and in hydrogen storage.

Properties

LiHe is a white, crystalline solid at room temperature. It has a high melting point of approximately 688 °C and a density of 0.78 g/cm³. The compound is highly reactive, especially with water, forming lithium hydroxide (LiOH) and releasing hydrogen gas (H₂) in the process:

\[ \text{LiH} + \text{H}_2\text{O} \rightarrow \text{LiOH} + \text{H}_2\uparrow \]

LiHe is also known for its high thermal conductivity and low electrical conductivity, making it useful in certain thermal management applications.

Synthesis

LiHe can be synthesized by the direct combination of lithium and hydrogen at elevated temperatures. The reaction is typically carried out at temperatures between 500 °C and 700 °C:

\[ 2\text{Li} + \text{H}_2 \rightarrow 2\text{LiH} \]

This process requires careful control of the reaction conditions to ensure the complete conversion of lithium to lithium hydride.

Applications

LiHe is used in a variety of applications due to its unique properties:

• Hydrogen Storage: LiHe is used in hydrogen storage systems due to its ability to absorb and release hydrogen gas.
• Desiccant: It is used as a drying agent in organic synthesis and other chemical processes.
• Nuclear Applications: LiHe is used in nuclear reactors as a neutron moderator and in the production of tritium.

Safety and Handling

LiHe is highly reactive, particularly with water and moisture in the air. It must be handled under an inert atmosphere, such as argon or nitrogen, to prevent unwanted reactions. Protective equipment, including gloves and goggles, should be worn when handling LiHe to prevent contact with skin and eyes.

Also see

• Lithium
• Hydrogen
• Ionic compound
• Desiccant
• Hydrogen storage