Uses of Alkali

The term alkali metals come from their water reactivity. About 0.03% of the earth’s crust contains the other alkali elements, such as lithium, rubidium, and cesium. Francium is a naturally radioactive isotope discovered in 1939.

Because alkali metals are reactive, usually found in combination with other elements, they generally extract and purify simple minerals like sylvite (KCl), halite (NaCl), and carnallite (KCl MgCl2 6H2O). The earth’s crust contains significantly more complex, water-insoluble minerals. Meteor ablation produces dilute sodium gas. Atomic oxygen and ozone react with sodium to form a meteor’s “tail” and a diffuse nightglow. Lithium and potassium, in smaller amounts, are also present.

The metals have ductility, silvery lustre, and excellent electrical and thermal conductivity. Lithium is the smallest metal, and lithium has a melting point of 179°C (354°F), whereas cesium has a melting point of 28.5°C (83.3°F). Alkali metal alloys may melt at −78 °C (−109 °F).

Uses of alkali metals

Sodium is the most important alkali metal in industrial application, and the metal reduces organic compounds and prepares several commercial compounds. Some nuclear reactors use it as a free metal heat transfer fluid. We use hundreds of thousands of tonnes of sodium compounds every year, including baking soda (NaHCO3), sodium carbonate (Na2CO3), salt (NaCl), and caustic soda (NaOH). Potassium is a less useful free metal than sodium. The production of fertilisers, however, requires large quantities of potassium salts. Lithium is in light metal alloys and as organic synthesis. The development of lightweight batteries is an important use of lithium. Cameras, mobile phones, and pacemakers use primary lithium batteries (non-rechargeable), and rechargeable lithium storage batteries for vehicles or energy storage are a hot research topic. Cesium metal vapour is in atomic clocks, which are precise time standards.

History

The ancients knew alkali metal salts. Neter (sodium carbonate) is a salt manufactured from vegetable ash and mentioned in the Old Testament. The invention of the component of gunpowder, saltpetre (potassium nitrate), in China in the 9th century and introduced in Europe by the 13th century.

Sir Humphry Davy, an English scientist, discovered potassium and sodium in 1807. Aqueous solutions of wood ashes are aqueous sodium solutions. The word sodium derives from the Italian soda, used in the Middle Ages for all alkalies.

Johan August Arfwedson, a Swedish scientist, discovered lithium in 1817 while studying petalite. The Greek word lithos derived lithium, meaning stone, and Davy created a minimal amount by electrolysing lithium chloride.

Robert Bunsen and Gustav Kirchhoff created a filtrate with two lines in the blue spectrum in 1860. They suggested the existence of a new alkali element named cesium, taken from the Latin caesius, meaning sky blue. After extracting alkalies from lepidolite, the same researchers separated another solution with two red spectral lines. They named the element in this solution rubidium after the Latin word for dark red, rubidus. Perey discover francium in 1939 at the Paris Radium Institute.

Sodium was a reagent in the 19th century to make aluminium. When the electrolytic technique for aluminium purification developed, it appeared that large-scale sodium usage would end. As a result of technological advancements in sodium electrolytic, sodium is now affordable for use in gasoline additives, pharmaceuticals, herbicide and pesticide manufacturing and metal refining reagent production. The Downs cell technology replaced the Castner process for continuous sodium hydroxide electrolysis in 1926. Electrolysis creates sodium metal and chlorine from molten sodium chloride–calcium chloride mixtures.

What are the uses of alkali metals in everyday life?

• Lithium, sodium, and potassium have a wide range of uses, but rubidium and caesium are only helpful in academic contexts. The everyday life uses of alkali metals are:
•  Batteries need lithium, and lithium oxide may help process silica.
• We can use lithium in lubricating greases, air purification, and aluminium production.
• The use of pure sodium in sodium-vapour lamps provides highly efficient light.
• Potassium is crucial in the biological system, and KCl is a fertiliser, whereas KOH is a soap component.
• Photoelectric cells use caesium.

The reaction of Alkali Metal with Water

Acid metals react with water to form basic hydroxides and hydrogen, and exothermic metal reactions increase enthalpy from lithium to cesium. Alkali metal floats during the process.

Potassium and sodium are less dense than water. The reaction enthalpy is large in heavier alkali metals, causing melt and surface rise. From lithium to cesium, the water reaction becomes faster, more exothermic, and more from lithium to cesium, the water reaction becomes faster, more exothermic.

2M + 2H2O → 2M+ + 2OH– + H2

Lithium has the highest electrode potential and hydration energy, making it more reactive and exothermic. Instead, lithium reacts with water slowly and non-explosively, and it has a limited rate of solubility and reaction due to its greater ionisation energy and covalent structure. Cesium is an ionic water-soluble compound.

The reaction enthalpy is greater than the latent heat of fusion. Consequently, the cesium melts into a liquid, and the process accelerates. Alkali metals may replace hydrogen from alkynes, ammonia, and alcohol.

Conclusion

Alkali metals have basic or alkaline metal hydroxides. The compounds are alkali metals because they form alkalies, strong bases that may neutralise acids when reacted with water.

The electronic configuration of alkali metals is [Noble gas] ns1. They are the first element in the periodic table’s first column. Sodium (Na), Potassium (K), Rubidium (Ru), Cesium (Cs), Lithium (Li), and Francium (Fr) are alkali elements with periods from one to seven. The radioactive element francium has a relatively short half-life.

Hydrogen (H) is a gas at normal temperatures and pressures, hence not regarded as an alkali metal. Under intense pressure, hydrogen may show qualities or change into an alkali metal.

Most alkali metals have several uses. Cesium atomic clocks are the most precise representation of time. The sodium-vapour lamp is an everyday use of sodium compounds—table salt, also known as sodium chloride, used since ancient times.