Hydrogen Element Properties and Information
Hydrogen Element Properties and Information
Hydrogen is the first element in the periodic table. Elements are arranged in the periodic table on the basis of atomic number. Atomic number is the number of protons in the nucleus of the atom. Hydrogen has an atomic number of 1. It is located in the Group 1 and Period 1 of the periodic table of elements. It is denoted by H. The name is derived from the Greek words ‘Hydro’ and ‘Genes’ and it means ‘Water Forming’.
Henry Cavendish is credited with the discovery of hydrogen in 1766. He was the first person who artificially produced it and recognised it as a discrete substance. Hydrogen was observed and collected by Robert Boyle in 1671 when he dissolved iron in hydrochloric acid but he didn’t recognise it as a separate substance.
Among all the elements, hydrogen is the most abundant. It is one of the constituent of water and it is a major constituent of organic matter. Every living organism is made up of organic matter mostly and they require water to stay alive. Sun is burning due to hydrogen and providing energy for life to flourish. It is most abundant element not only on earth but the entire universe. Among all the detectable matter, atomic hydrogen makes up to 75% of the total matter by mass.
Physical Properties
- It is colourless, odourless and tasteless.
- The atomic mass of hydrogen is 1.008
- The melting point of hydrogen is -259.2°C
- The boiling point of hydrogen is -252.8°C
- The density of hydrogen is about 0.082 in S.I. units at 20°C
- There are three isotopes of hydrogen; Protium, Deuterium and Tritium. Protium makes up to 99.985% of all the hydrogen. Deuterium makes approximately 0.015% of all the hydrogen. Tritium is very rare and it is naturally available only in trace quantities though it can be produced by some nuclear reactions.
Chemical Properties
- Hydrogen is flammable; in fact it is the most flammable material among all the known substances.
- Many metals can absorb hydrogen. If steel absorbs hydrogen then it becomes brittle which results in failure of equipment.
- At normal temperatures hydrogen is not very reactive but a catalyst can be used to increase the rate of reaction. Hydrogen is very reactive at high temperatures.
- Atomic hydrogen is a very good reducing agent which easily reduces oxides and chlorides of many metals into free metals.
- Hydrogen reacts with oxygen to form water. This is a very slow reaction without using a catalyst.
- Hydrogen gas forms explosive mixture at 4-74% in air. It spontaneously ignites at 500°C in air. It means 500°C is its autoignition temperature in air.
- Hydrogen can react and form compounds with more electronegative elements such as halogens and oxygen. It can also react with less electronegative elements and form hydrides.
- Hydrogen can form a wide range of products after reacting with carbon. The products are called hydrocarbons and they are generally referred to as organic compounds.
Methods of Production
- Bosch Process: Steam reforming of natural gas is a popular method used to produce hydrogen in bulk for commercial use. Methane is reacted with water in form of steam to produce hydrogen and carbon monoxide. Reaction is done at temperatures of 700-1100°C and 20 atm. Normally excess of water is used and additional hydrogen is recovered from carbon monoxide by water-gas shift reaction.
- Electrolysis: Electrolysis of water produces hydrogen and oxygen. Hydrogen forms at the cathode and oxygen forms at the anode.
- Metal-Acid: Many metals, especially the alkali and alkaline earth metals such as aluminium, zinc, manganese and iron react with aqueous acid to produce Hydrogen.
Relevance in Chemical and Related Industries
- For Hydrogenation: Hydrogenation implies reaction of hydrogen with substance or a compound. Ammonia is produced by hydrogenation of nitrogen and it is a popular method industrially because the process requires very less power as compared to other methods. Unsaturated oil and fats are converted to saturated oil and fats by the method of hydrogenation. Hydrogenation of carbon dioxide produces methanol.
- In iron and steel industries: Hydrogen reacts with certain ores and in the process of reaction it does not produce carbon dioxide like traditional methods. It produces water alternatively. Reducing ores with hydrogen is a relatively cleaner process.
- In Petrochemical industries: Hydrogen is very important for treatment and upgradation of fossil fuels. Many of the reactions involving hydrogen serve to breakdown single bonds between carbon-carbon and carbon-heteroatom, they are collectively called hydrogenolysis. Some of the specific reactions are hydroalkylation, to form simpler aromatic hydrocarbons devoid of functional groups; hydrodesulfarisation, to remove sulfur from natural gas or petroleum products; hydrocraking, for catalytic cracking.
- In Leak Detection: Hydrogen is used as a tracer gas which in chemical and related industries and also many industries not related to the chemical field. It is popular because it is able to detect leaks even at minute levels. It is used either in pure form or sometime mixed with nitrogen. In food industry hydrogen is used for food package leak testing.
Relevance in Other Industries
- In Semiconductor industries: It is used as an electron donor for various oxide materials, zinc oxide, magnesium oxide, tin oxide, cadmium oxide etc. Hydrogen is also employed to saturate broken bonds of amorphous carbon and amorphous silicon.
- In Power Stations: Hydrogen has the highest specific heat and thermal conductivity among all gases and also its density and viscosity is low due to which it is generally used as a coolant in power stations.
- In Welding: Atomic Hydrogen Welding method uses an arc between two electrodes made up of tungsten. It uses hydrogen as a shielding gas.
Health Effects on Exposure
- Burning: Hydrogen is very flammable and when it comes in contact with spark and oxygen it may burn anyone in or near the source.
- Asphyxiation: If the hydrogen is inhaled in high concentration then it causes oxygen deficit which leads to suffocation. It causes dizziness, drowsiness, nausea, vomiting and unconsciousness. It prolonged exposure it causes the skin to turn blue and in some cases even death may occur.
Effects on Surroundings
- Explosion: If 4-74% of hydrogen accumulates in air then it sparks and burns and expands very rapidly. If this occurs in a closed space then there is a danger loss of lives and properties.
- On Ventilation: If the closed space does not have proper ventilation then even if the hydrogen does not find a spark, it will cause the surroundings to become oxygen deficit. If there is proper ventilation then the hydrogen gas will be dissipated very rapidly.
- On Animals and Plants: Animals will pose threat of asphyxiation or burning. Plants may also pose problem of frosting in some cases due to rapidly expanding gas.
Reference: Hydrogen Element
