Which hydride has a low melting point


Lithium is the first alkali metal on the periodic table of the elements. In nature it is found in a mixed form of the isotopes Li6 and Li7. Lithium is the lightest metal in solid form, it is soft, with a low melting point, and reactive. Many of its physical and chemical properties are more similar to those of the alkaline earth metals than to those of its own group.

The main industrial application of lithium is in lithium stearate, as a lubricating grease and thickening agent. The lithium compounds find other important uses in pottery, especially in porcelain glaze; As a service life and performance-extending additive for alkaline batteries and for gas and brass welding.
Lithium is a moderately abundant element and its share in the earth's crust is 65 ppm (parts per million). This places lithium in terms of quantity among nickel, copper and tungsten and above the quantity of cerium and tin.

Among the most important properties of lithium we find its high specific heat capacity, the very large temperature difference in the liquid state, high thermal conductivity, low viscosity and very low density. Metallic lithium is soluble in short allphatic polyamines as well as in ethylamine. It does not dissolve in hydrocarbons.

Lithium enters into a large number of reactions with organic reactants as well as with inorganic reactants. It reacts with oxygen to form monoxide and hyperoxide. It is the only alkaline metal that reacts with nitrogen at ambient temperature to produce a black nitrure. It reacts violently with water and easily with hydrogen at almost 500ºC
(930 ° F) to form lithium hydride. Metallic lithium reacts extremely violently with water. Lithium reacts directly with the carbon to form carbonides.
It easily binds with halogens and forms halides with bright emission spectral lines. Although it does not react with paraffin hydrocarbons, it does react in addition reactions with the alkenes, replacing the double bonds and diene groups. It also reacts with the acetylene compounds and forms lithium acetylene, which is important in vitamin A synthesis.

The main lithium compound is lithium hydroxide. It is a white powder and it is made from monohydrate lithium hydroxide. The carbonate can be used as a tonic in the pottery industry and medicine. Bromine and the two lithium chloride forms concentrated saline solution, which have the property of absorbing moisture in a wide range of temperature. Such salt solutions are z. B. used in air conditioning systems.

Health effects of lithium

Lithium is flammable. Many reactions can cause fire or explosion. There are irritating or toxic fumes (or the gases) in the fire.
Lithium is also explosive: the risk of fire and explosion arises in contact with flammable substances and water. If lithium gases are inhaled, this can lead to burning irritation symptoms, coughing, difficult breathing or short breathing and an inflamed larynx. Symptoms can be delayed.
Contact with the skin can cause redness, skin irritation, pain and blisters. Eyes can be red, sore, and burned severely. Oral ingestion of lithium may cause abdominal cramps.
This can lead to burning pain, nausea, vomiting, weakness, or a coma.
The substance can enter the body by inhalation of the aerosol and by ingestion.

Inhalation hazards: Evaporation at 20 ° C is harmless. However, a harmful concentration of the particles can be reached quickly if they are finely divided.

Acute exposure: The substance is extremely corrosive in contact with eyes and skin and in the respiratory tract. Corrosive on ingestion. Inhalation of the substance can cause pulmonary edema. The symptoms of pulmonary edema are often not obvious and only noticeable after a few hours due to physical weakness. Rest and medical treatment are required. An appropriate spray should be inhaled immediately by a doctor or a person authorized by him / her.

Chemical hazards: A strong heating of the lithium can cause violent fires or explosions. The substance can spontaneously ignite on contact with air if it is finely divided. Toxic fumes are formed when heated. Lithium reacts violently with strong oxidizing agents, acids and many compounds (hydrocarbons, halogens, concrete, sand and asbestos). When reacting with water, hydrogen gas and corrosive vapors of lithium hydroxide are formed, which are highly flammable.

Environmental effects of lithium

Metallic lithium reacts with nitrogen, oxygen and water vapor in the presence of air. As a result, an oxide layer forms on the lithium surface, creating the hydroxide (LiOH), lithium carbonate (Li2CO3) and lithium nitride (Li3N). Lithium hydroxide poses a potential significant hazard because it is extremely corrosive. Special attention should be given to aquatic organisms.

Lithium and water

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