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- water. (H2O) dihydrogen monoxide; H2O.
- A colorless, tasteless liquid with some very peculiar properties that stem from the bent H-O-H structure of its molecules.
- water gas. blue gas; synthesis gas.
- A fuel gas used in industrial synthesis of organic chemicals, and in welding, glassmaking, and other high-temperature industrial applications. Water gas made by passing steam over a bed of hot coal or coke. It consists mainly of of carbon monoxide (CO) and hydrogen (H2), contaminated with small amounts of CO2, N2, CH4, and O2.
- water hardness. hard water. Compare with water softener.
- Hard water is water contaminated with compounds of calcium and magnesium. Dissolved iron, manganese, and strontium compounds can also contribute to the "total hardness" of the water, which is usually expressed as ppm CaCO3. Water with a hardness over 80 ppm CaCO3 is often treated with water softeners, since hard water produces scale in hot water pipes and boilers and lowers the effectiveness of detergents.
- water of crystallization. water of hydration.
- Water that is stoichiometrically bound in a crystal; for example, the waters in copper sulfate pentahydrate.
- water softener. soft water; water softening. Compare with water hardness.
- A material that lowers water hardness when dissolved in water. For example, sodium carbonate ("washing soda") softens water by precipitating Ca2+ ions as CaCO3. Zeolites soften water by exchanging Ca2+ ions with Na+ ions.
- water softening. Compare with water softener and water hardness.
- Removal of Ca2+ and Mg2+ from water to prevent undesirable precipitation reactions from occurring in plumbing, pools, washwater, and boilers.
- wavefunction. ()
- A mathematical function that gives the amplitude of a wave as a function of position (and sometimes, as a function of time and/or electron spin). Wavefunctions are used in chemistry to represent the behavior of electrons bound in atoms or molecules.
- The distance between adjacent peaks (or adjacent troughs) on a wave. Varying the wavelength of light changes its color; varying the wavelength of sound changes its pitch.
- An oscillating motion that moves outward from the source of some disturbance (ripples running away from a pebble tossed in a pond). Waves transmit the energy of the disturbance away from its source.
- The number of wave crests per unit distance. Wavenumber is the reciprocal of wavelength. Wavenumbers are used extensively in infrared spectroscopy, and usually have units of cm-1.
- wave-particle duality. The observation that electrons; photons; and other very small entities behave like particles in some experiments and like waves in others.. Compare with quantum
- An ester formed from long-chain fatty acids and alcohols that is usually solid at room temperature.
- weak acid. Compare with strong acid.
- An acid that only partially dissociates into hydrogen ions and anions in solution. Weak acids are weak electrolytes. Recognize weak acids by learning the six common strong acids; any acid that doesn't appear on the list of strong acids is usually a weak acid.
- weak base. Compare with strong base.
- A base that only partially dissociates into ions in solution. Weak bases are weak electrolytes. Ammonia is an example of a weak base; the reaction NH3(aq) + H2O(l) = NH4_+(aq) + OH-(aq) is reversible.
- weak electrolyte. Compare with strong electrolyte.
- A weak electrolyte is a solute that incompletely dissociates into ions in solution. For example, acetic acid partially dissociates into acetate ions and hydrogen ions, so that an acetic acid solution contains both molecules and ions. A solution of a weak electrolyte can conduct electricity, but usually not as well as a strong electrolyte because there are fewer ions to carry the charge from one electrode to the other.
- weak ligand. weak field ligand. Compare with strong field ligand.
- A ligand that causes a small crystal field splitting which results in a high-spin complex.
- weight. (W) Compare with mass.
- Weight is the force exerted by an object in a gravitational field. The weight of an object (W) arises from its mass (m): W = mg where g is the acceleration due to gravity (about 9.8 m/s2 on Earth).
- wetting. wet.
- Covering with a surface with thin film of liquid. Liquid beads up on a surface if it cannot wet it.
- work. Compare with heat.
- Work is the energy required to move an object against an opposing force. Work is usually expressed as a force times a displacement. Dropping a stone from a window involves no work, because there is no force opposing the motion (unless you consider air friction...). Pushing against a stone wall involves no work, unless the stone wall actually moves.