Chlorine, often in the form of calcium hypochlorite, Ca(OCl)2, is added to swimming pools to kill microorganisms.  The acidic form of hypochlorite, hypochlorous acid (HOCl), is the effective antibiotic: OCl– + H3O+ –> HOCl + H2O This means that pool water must be kept acidic enough to allow HOCl to form, but not too acidic (you don’t […]

When a fluorine atom gains an electron, it becomes a fluoride ion: F + electron –> F– Teeth are often treated with fluoride.  This is because when fluoride substitutes for hydroxide in hydroxyapatite (the mineral in teeth), a stronger mineral results: Ca10(PO4)6(OH)2 + 2 F– –> Ca10(PO4)6(F)2 + 2 OH– next element           […]

Oxygen is necessary for the combustion (burning) of carbon-containing fuels.  For example, the combustion of methane is represented by: CH4 (g) + 2 O2 (g) –> CO2 (g) + 2 H2O (g) Combustion of carbon-containing fuels is the primary source of energy for a variety of processes on earth.  Oxygen is also required for the […]

Nitrogen is found in large amounts in fertilizer.  One simple example of a nitrogen-containing explosive is nitrogen triiodide (NI3).   Nitrogen triiodide, like many explosives, forms N2 gas upon detonation: 2 NI3 (s) –> 3 I2 (g) + N2 (g) The formation of N2 (g) releases almost a megajoule per mole.  This energy release upon the […]

Hydrogen is the most abundant element in the universe.  On Earth, it is usually found as a diatomic gas (H2 ).  The reaction of hydrogen gas with oxygen gas to form water releases a tremendous amount of energy: 2H2 (g) + O2 (g) –> 2 H2 O (l) + Energy As a result of the […]