Molecule of the Week

January 20, 2002

Space filling model of water

 

Water - H2O

molecular mass 18.02 g/mol
boiling point (1 atm)  373 K
density (277.13K) 1.000 g/mL
acid dissociation constant 1 X 10-14
heat capacity 4.18 J/K mol
total amount in Earth's mantle 2 X 1023 kg


Water makes up most of the mass of most living things, including humans. Water is the solvent of choice for most ionic reactions, for many acids and bases, and is used in large quantities in many industrial processes.

Chemically, it has some unusual properties. Hydrogen bonding between adjacent molecules causes it to have a higher than expected boiling point and high viscosity, as well as resulting in expansion upon freezing.

In Chem 101, chemical equilibria and acid-base properties are all discussed in terms of substances dissolved in water. This is because water is the most commonly encountered solvent, and because it is the solvent in all biological processes.

Links with more information on water:


structure of water and biological properties

magnetic water treatment and other scams

water chemistry relevant to fish in aquariums


water and beer





Evidence of water-erosion on Mars

click to enlarge

A recent NASA photo of the surface of Mars showing features that are thought to have been caused by liquid water.

more info on Mars exploration




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