hydrogen

• Hydrogen is the lightest element
• Hydrogen is the most abundant element
• Hydrogen is present in the maximum amount in the Sun and stars
• Henry Cavendish discovered hydrogen gas in 1776 by preparing it through the action of acid on various metals
• Hydrogen is the main component of Jupiter and other gas giant planets
• Hydrogen can be obtained by displacement reactions
• Pure water does not conduct electricity, but by adding a few drops of dilute sulfuric acid, it conducts electricity
• Electrolysis of water is the process of passing an electric current through acidified water, which dissociates into hydrogen and oxygen
• Electrolysis is the process of decomposition of a chemical compound in the dissolved state or molten state by the passage of an electric current
• Electrolysis requires an electrolytic cell, electrolyte, electrodes, and a power supply
• An electrolytic cell is a container made of glass where electrolysis is carried out
• An electrolyte is a compound that conducts electric current in the molten state or solution state and undergoes chemical decomposition
• Electrodes are conduction rods that allow the electric current to enter or leave the electrolyte, usually made of inert substances
• Lead is not used in the preparation of hydrogen because the reaction is slow and the products formed are insoluble, forming a layer over the metal preventing further reaction
• Metals such as lithium, potassium, and sodium are called alkali metals
• The hydroxides of these metals are called alkalis
• Metals like Zn, Al, Pb react with hot alkalis to give soluble salts and liberate hydrogen
• Hydrogen can be prepared in the lab by reacting granulated zinc with dilute sulfuric acid or dilute hydrochloric acid
• Hydrogen gas is collected with downward displacement of water
• Precautions for the preparation of hydrogen include ensuring the apparatus is airtight, keeping flames away, collecting gas only after all air has escaped, and using downward displacement of water
• Granulated zinc is preferred for the reaction as it contains copper as an impurity, which speeds up the reaction smoothly
• Zinc is preferred over other metals for hydrogen preparation because more reactive metals are explosive and uncontrollable, and calcium and magnesium are expensive
• Carl Bosch invented the Bosch process for preparing hydrogen on a manufacturing scale by passing a mixture of steam and water gas over a suitable catalyst
• Water gas is a mixture of carbon monoxide and hydrogen
• A promoter is a substance that increases the efficiency of a catalyst
• Properties of hydrogen gas: colorless, odorless, tasteless, non-poisonous, density of 0.09g/dm3, insoluble in water, best conductor of heat among all gases
• The melting point of hydrogen is -259 degrees Celsius and the boiling point is -253 degrees Celsius
• Hydrogen is highly inflammable and burns with a pop sound
• Chemical properties of hydrogen: neutral to litmus paper, combustible, reacts with nitrogen, oxygen, sulfur, and chlorine
• Oxidation is the process of adding oxygen or removing hydrogen, reduction is adding hydrogen or removing oxygen
• A redox reaction is a reaction where oxidation and reduction take place simultaneously
• The reaction between lead oxide and hydrogen is a redox reaction
• Hydrogen reacts with carbon dioxide at a temperature of 300 to 400°C and high pressure with nickel as a catalyst to produce methane and water