Lithium hydride is a compound composed of lithium and hydrogen. It is highly reactive and widely used in various applications, including energy storage and nuclear reactions.
| IUPAC Name | Lithium hydride |
| Molecular Formula | LiH |
| CAS Number | 7580-67-8 |
| Synonyms | Lithium monohydride, Lithane, Lithiumhydride, hydride lithium |
| InChI | InChI=1S/Li.H |
Lithium Hydride Properties
Lithium Hydride Formula
The formula of lithium monohydride is LiH. It consists of one lithium atom bonded to one hydrogen atom. This simple and concise formula represents the elemental composition of lithium monohydride.
Lithium Hydride Molar Mass
The molar mass of lithium monohydride is calculated by adding the atomic masses of lithium (Li) and hydrogen (H). It is approximately 7.95 grams per mole (g/mol). Molar mass is essential for various calculations in chemistry, such as determining the amount of substance in a given sample.
Lithium Hydride Boiling Point
Lithium monohydride has a high boiling point of around 1,350 degrees Celsius (2,462 degrees Fahrenheit). This indicates that it requires a significant amount of energy to convert the solid compound into a gaseous state.
Lithium Hydride Melting Point
The melting point of lithium monohydride is quite high, at about 688 degrees Celsius (1,270 degrees Fahrenheit). This temperature represents the point at which the solid compound transforms into a liquid state upon heating.
Lithium Hydride Density g/mL
The density of lithium monohydride is approximately 0.82 grams per milliliter (g/mL). This value indicates that lithium monohydride is a relatively dense compound, which means it has a significant mass per unit volume.
Lithium Hydride Molecular Weight
The molecular weight of lithium monohydride is determined by adding the atomic weights of lithium and hydrogen. It is approximately 7.95 grams per mole (g/mol). Molecular weight is crucial in various chemical calculations, including determining the stoichiometry of reactions.
Lithium Hydride Structure
Lithium monohydride has a crystal structure in which lithium cations (Li+) and hydride anions (H-) are arranged in a three-dimensional lattice. The lithium and hydrogen atoms are held together by strong ionic bonds.
Lithium Hydride Solubility
Lithium monohydride is sparingly soluble in water. It reacts with water to form lithium hydroxide (LiOH) and hydrogen gas (H2). This limited solubility is due to the highly ionic nature of lithium monohydride, which makes it less likely to dissolve in polar solvents like water.
| Appearance | White solid |
| Specific Gravity | 0.82 |
| Color | White |
| Odor | Odorless |
| Molar Mass | 7.95 g/mol |
| Density | 0.82 g/mL |
| Melting Point | 688°C (1,270°F) |
| Boiling Point | 1,350°C (2,462°F) |
| Flash Point | Not applicable |
| Water Solubility | Reacts with water to form form lithium hydroxide (LiOH) & hydrogen gas (H2) |
| Solubility | Sparingly soluble |
| Vapor Pressure | Not applicable |
| Vapor Density | Not applicable |
| pKa | Not applicable |
| pH | Not applicable |
Lithium Hydride Safety and Hazards
Lithium monohydride poses several safety hazards. It reacts violently with water, releasing flammable hydrogen gas and producing corrosive lithium hydroxide. Contact with moisture or air can cause the formation of highly flammable hydrogen gas. It should be handled with extreme caution to avoid accidental ignition or explosion. The compound is also highly reactive with acids, releasing toxic hydrogen gas. Lithium monohydride can cause severe skin and eye irritation, and inhalation of its dust or fumes may lead to respiratory distress. Proper protective equipment, such as gloves and goggles, should be worn when working with lithium monohydride, and it should be stored in a dry and well-ventilated area.
| Hazard Symbols | Flammable, Corrosive |
| Safety Description | Highly reactive and flammable. Handle with extreme caution. Avoid contact with water, air, and acids. |
| UN IDs | UN 1414 |
| HS Code | 2850.00.10 |
| Hazard Class | 4.3 (Dangerous when wet) |
| Packing Group | I (Great danger) |
| Toxicity | Toxic upon ingestion or inhalation. Can cause severe skin and eye irritation. |
Lithium Hydride Synthesis Methods
Various methods can synthesize lithium monohydride.
One common method involves the direct combination of lithium metal with hydrogen gas. The reaction takes place at high temperatures, typically above 600 degrees Celsius (1,112 degrees Fahrenheit), in a controlled environment. The lithium metal reacts with the hydrogen gas, forming lithium monohydride.
Another method is the reduction of lithium amide (LiNH2) with lithium metal. This reaction occurs at lower temperatures, around 350-400 degrees Celsius (662-752 degrees Fahrenheit). Reacting lithium amide with lithium metal produces lithium monohydride.
The synthesis of lithium monohydride can also occur by combining lithium borohydride (LiBH4) with lithium monohydride itself. The reaction takes place at high temperatures, typically around 400 degrees Celsius (752 degrees Fahrenheit). This method allows for the formation of lithium monohydride from readily available lithium borohydride.
Additionally, lithium aluminum hydride (LiAlH4) serves as a starting material for the synthesis of lithium monohydride. Under controlled conditions, lithium aluminum hydride reacts with lithium metal, resulting in the formation of lithium monohydride.
It is worth noting that these methods require careful handling and strict control of reaction conditions due to the highly reactive nature of lithium monohydride. Safety precautions, such as working in an inert atmosphere and using proper protective equipment, should be followed during the synthesis process.
Lithium Hydride Uses
Lithium monohydride finds various applications due to its unique properties and reactivity. Here are some of its uses:
- Lithium monohydride enables the development of advanced hydrogen storage systems, facilitating efficient and compact energy storage solutions.
- In nuclear reactions, it acts as a neutron source and finds application in research facilities and nuclear power plants.
- Organic synthesis utilizes lithium monohydride as a potent reducing agent to reduce various functional groups.
- It generates hydrogen gas through its reaction with water or acids, making it valuable for on-site hydrogen production.
- When combined with other propellants, lithium monohydride contributes to energy generation and thrust in rocket engines.
- Lithium monohydride plays a role in the production of deuterium gas, which has applications in nuclear power generation and scientific research.
- Hydrometallurgical processes employ lithium monohydride to produce various metals like titanium and zirconium.
- It serves as a precursor or reagent in chemical synthesis, aiding in the formation of organic and inorganic compounds.
- Certain pyrotechnic formulations use lithium monohydride to generate intense heat and gas upon reaction.
- Hydrogenation reactions utilize lithium monohydride to add hydrogen to unsaturated compounds, forming saturated compounds.
These diverse applications highlight the versatility and significance of lithium monohydride in multiple industries and scientific endeavors.
Questions:
Q: What is the formula of the hydride formed by lithium?
A: The formula of the monohydride formed by lithium is LiH.
Q: Does lithium hydride reduce double bonds?
A: Yes, lithium monohydride can reduce double bonds in organic compounds.
Q: What does lithium hydride reduce?
A: LiH is a powerful reducing agent commonly used to reduce various functional groups in organic synthesis.
Q: Is lithium hydride ionic or covalent?
A: Lithium monohydride is an ionic compound, consisting of Li+ cations and H- anions.
Q: What is the difference between lithium-ion and nickel-metal hydride batteries?
A: Li-ion batteries offer higher energy density, longer lifespan, and lighter weight compared to nickel-metal hydride batteries.
Q: What is the lithium hydride mechanism?
A: The mechanism of lithium monohydride varies depending on its specific reaction and application. It can act as a reducing agent or react with water, acids, or other compounds.
Q: Is lithium hydride a nucleophile?
A: Yes, lithium monohydride can act as a nucleophile in certain chemical reactions.
Q: What items use lithium hydride to create?
A: Lithium monohydride is primarily used in industrial applications, such as energy storage systems, nuclear reactions, hydrogen generation, and chemical synthesis.
Q: Does lithium hydride reduce alcohols?
A: Lithium monohydride can reduce alcohols to corresponding alkanes or aldehydes depending on reaction conditions and other factors.