Solids are similar to liquids in that both are condensed states, with particles that are far closer together than those of a gas.

The first theory explaining the mechanism of melting in bulk was proposed by Lindemann, who used the vibration of atoms in the crystal to explain the melting transition. When considered as the temperature of the reverse change from liquid to solid, it is called the freezing point or crystallization point. The melting point of a substance depends on pressure and is usually specified at standard pressure. Adding heat will convert the solid into a liquid with no temperature change. In thermodynamics, the melting point defines a condition where the solid and liquid can exist in equilibrium. When considered as the temperature of the reverse change from vapor to liquid, it is called the condensation point. The pressure at which vaporization (boiling) starts to occur for a given temperature is called the saturation pressure. The temperature at which vaporization (boiling) starts to occur for a given pressure is called the saturation temperature or boiling point. In thermodynamics, saturationdefines a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure. Note that these points are associated with the standard atmospheric pressure. Additionally, chromium is used as a catalyst in dying and in the tanning of leather, to make moulds for firing bricks and its oxide is used to manufacture magnetic tape.Chromium – Melting Point and Boiling Point Its salts are used to colour glass, due to the emerald green colour, and chromium is also used to produce synthetic rubies. Pure chromium is also used to manufacture non-ferrous alloys and super alloys, which can be used in magnets, in metallurgy to impart corrosion resistance and shiny finish and as dyes and paints. The other two major uses are in the form of alloys, such as stainless steel and for plating purposes to give steel a polished silvery coating. 20% of chromite mined is used in refractories, foundry mould sand and other non metallurgical uses. The USA is the largest end user of chromium, although it does not have any of its own resources. South Africa and Russia produce half of the world’s chromium through chromite ore and ferro-chromium, with Zimbabwe producing 8%. 14 million tonnes of chromite ore is extracted, whereas chromium production itself is only around 20,000 tonnes, with somewhere in the order of 1 billion tonnes of chromite ore in reserves. In 1848 large deposits were established in Turkey, followed by South Africa, Zimbabwe, Finland, India, Brazil, Albania, Kazakhstan and the Philippines. The first commercially exploitable deposits were discovered in Maryland, USA, and fulfilled the demand of commercial chromium for 30 years. In 1848, large deposits were established in Turkey and this became the next main source. The first commercially exploitable deposits were discovered in Maryland, USA, and fulfilled the demand of commercial chromium for around 30 years. By concluding that lead was present, he proceeded to precipitate the lead out of the solution and concentrated the remains, although it was not until one year later that he isolated the chromium element. This mineral was referred to as Siberian red lead (now known as crocoite, a form of lead chromate). Vauquelin came across a bright red mineral that had been discovered in a Siberian gold mine in 1766. Chromium is a beautiful looking metal when polished, and the only reason that it is not used in jewellery as an alternative to silver is that it is too cheap to be taken seriously.Ĭhromium was both discovered and isolated in 1798 by the French chemist Nicholas Louis Vauquelin in Paris. Chromium will dissolve in hydrochloric and sulphuric acids but not phosphoric acid, due to reaction and formation of a protective layer on the surface.

This name was given as all chromium compounds are coloured. The name chromium comes from the Greek word “chroma” meaning colour. Chromium can be polished to an extremely high shine but due to its reactivity with oxygen, an oxide layer forms and dulls the surface. Chromium is a hard, silvery metal with a blue tinge and belongs to Group 6 of the Periodic Table it is the 21st most abundant element in the Earth’s crust.

Chromium melting point