Deionized water (DI water or de-ionized water; also spelled deionised water, see spelling differences) is water that lacks ions, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. This means it has been purified from all other ions except H₃O⁺ and OH⁻, but it may still contain other non-ionic types of impurities such as organic compounds. This type of water is produced using an ion exchange process. Deionized water is similar to distilled water, in that it is useful for scientific experiments where the presence of impurities may be undesirable. The differences in the spellings of British English and American English are as follows: Spelling differences between U.S. usage on one side and British and Commonwealth usage on the other are generally more conspicuous than spelling differences within the Commonwealth. ... Impact of a drop of water Water is a chemical substance that is essential to all known forms of life. ... “Multivalent” redirects here. ... A cation is an ion with positive charge. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Standard atomic weight 63. ... An anion is an ion with negative charge. ... The chloride ion is formed when the element chlorine picks up one electron to form an anion (negatively-charged ion) Cl−. The salts of hydrochloric acid HCl contain chloride ions and are also called chlorides. ... A bromide is a phrase, or person who uses phrases, which have been used and repeated so many times as to become either insincere in their meaning, or seem like an attempt at trying to explain the obvious. ... In chemistry, hydronium is the common name for the cation H3O+ derived from protonation of water. ... Hydroxide is a polyatomic ion consisting of oxygen and hydrogen: OH− It has a charge of −1. ... Ion exchange is a process in which ions are exchanged between a solution and an ion exchanger, an insoluble solid or gel. ... Distilled water is water that has virtually all of its impurities removed through distillation (boiling the water and re-condensing the steam into a clean container, leaving contaminants behind). ... Part of a scientific laboratory at the University of Cologne. ... In the scientific method, an experiment (Latin: ex-+-periri, of (or from) trying), is a set of actions of going to the bathroom. ...

Properties

The lack of ions causes the water's resistivity to increase. Ultra-pure deionized water can have a theoretical maximum resistivity up to 18.31 MΩ·cm, compared to around 15 kΩ·cm for common tap water. Deionized water's high resistivity allows it, in some very highly specialized instances, to be used as a coolant in direct contact with high-voltage electrical equipment. Because of its high relative dielectric constant (~80), it is also used (for short durations) as a high voltage dielectric in many pulsed power applications, such as Sandia's Z Machine. Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of electric current. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Pulsed power is the science and technology of accumulating energy over a relatively long period of time and releasing it very quickly. ... Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar...

pH values

pH is a logarithmic measurement of proton presence; the true pH of deionized water is 7.0, because the ionization constant of water (K_w) ~ 10^-14, so p[K_w] = 14, and pH + pOH = p[K_w]. The correct title of this article is . ...

In practice, the indication from chemical indicators can give a value of usually between pH 5.0 and pH 9.0 depending on the indicator used (the indication being the ions introduced by the indicator itself, its solvent and its impurities). Electronic pH meters will output an unpredictable value since the absence of ions in the liquid means that the two parts of the electrode are insulated from each other and thus would generate no EMF. In practice since absolutely pure water is an unattainable goal, the liquid will contain a very small amount of ions, but the current this would allow the probe to generate will be far smaller than that required to operate the metering circuit.

pH meter electrodes should not be immersed in deionised water for prolonged periods as the lack of any ions 'sucks' them out of the electrode degrading its performance. Deionised water should be used for cleaning only rarely as the effect is cumulative. Electrodes should be cleaned using proper cleaning solution (usually very acidic), and rinsed between samples in a pH neutral liquid such as tap water or pH 7.0 buffer solution (but ideally in the next sample to be tested).

Deionized water will quickly acquire a pH when exposed to air. Carbon dioxide, present in the atmosphere, will dissolve in the water, introducing ions and giving an acidic pH of around 5.0. The limited buffering capacity of DI water will not inhibit the formation of carbonic acid H₂CO₃. Boiling the water will remove the carbon dioxide to restore the absence of a pH value. Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3. ...

Ultrapure deionized water

The uses of ultrapure deionized water are many and varied, often having applications in scientific experimentation such as when very pure chemical reagent solutions are needed in a chemical reaction or when a biological growth medium needs to be sterile and very pure. A reagent or reactant is any substance used in a chemical reaction. ...

Deionization

Process utilizing specially-manufactured ion exchange resins which remove ionized salts from water can theoretically remove 100% of salts. Deionization typically does not remove organics, virus or bacteria, except through “accidental” trapping in the resin and specially made strong base anion resins which will remove gram-negative bacteria.

Uses

DI water is necessary in clinical and medical laboratories, where its addition to various reagents and solvents enable accurate measurements, often on automated machines which use very little specimen (i.e. plasma, serum, etc.)

DI water is also used extensively in the semiconductor industry to process and clean silicon wafers and sometimes in the optics industry when very highly clean optical surfaces are required for coating. DI water is also often used as a final rinse when washing scientific glassware. An etched silicon wafer In microelectronics, a wafer is a thin slice of semiconducting material, such as a silicon crystal, upon which microcircuits are constructed by doping (for example, diffusion or ion implantation), etching, and deposition of various materials. ...

Deionized water is very often used as an "ingredient" in many cosmetics and pharmaceuticals where it is sometimes referred to as "aqua" on product ingredient labels. This use again owes to its lack of potential for causing undesired chemical reactions due to impurities.

A recent use of DI water is that of a final rinse in some car washes where, because it contains no dissolved solutes, the car dries without leaving any spots. Another use of deionized water is in window cleaning, where window cleaners use pumped systems to brush and rinse windows with deionized water again without leaving any spots. Typical American multi-bay car wash, with an automatic touchless bay at the far left and manual bays on the right. ...

Deionized water is used in freshwater aquariums. Since it does not contain impurities such as copper and chlorine, it keeps fish free from diseases, as well as avoiding the build-up of algae on aquarium plants, due to its lack of phosphate and silicate. Deionized water should be re-mineralized before used in aquaria, since it also lacks many macro and micro-nutrients needed by both plants and fish. For other uses, see Aquarium (disambiguation). ...

Deionized water has also recently found a use in an up to date version of water fog fire extinguishing systems. Such systems can be used in sensitive environments such as where high voltage electrical and sensitive electronic equipment is used. The 'sprinkler' nozzles use much finer spray jets and operate at up 350 Bar (5000 p.s.i.) of pressure. The extremely fine mist produced takes the heat out of a fire rapidly and the deionized water coupled with the fine droplets is non conducting and does not damage sensitive equipment, not already damaged by fire. The system is perfectly safe to discharge when personnel are present. Apart from getting a little damp, there are no other hazards associated with the system.

Small scale water deionizing for hydrogen production

For small scale production of hydrogen, water purifiers are installed to prevent formation of minerals on the surface of the electrodes and to remove organics and chlorine from utility water. First the water passes through a 20 micron interference (mesh or screen filter) filter to remove sand and dust particles, second, a charcoal filter (activated carbon) to remove organics and chlorine, third stage, a de-ionizing filter to remove metallic ions. A test can be done before and after the filter for proper functioning on barium, calcium, potassium, magnesium, sodium and silicon. Hydrogen production is done in bulk today from hydrocarbon fossil fuels via a chemical path. ... Control room and schematics of the water purification plant to Bret lake. ... A mesh is similar to fabric or a web in that it has many connected or weaved pieces. ... A screen filter is a type of filter utilizing a rigid or flexible screen to separate sand and other fine particles out of water for irrigation or other applications. ... Carbon filtering is a method of water purification that uses a block of activated carbon to remove contaminants and impurities, utilizing chemical adsorption. ... Activated carbon from a water filter used for carbon filtering in powder and block form Activated carbon, also called activated charcoal or activated coal, is a general term which covers carbon material mostly derived from charcoal. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... General Name, Symbol, Number barium, Ba, 56 Chemical series alkaline earth metals Group, Period, Block 2, 6, s Appearance silvery white Atomic mass 137. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... It has been suggested that Silicons ranking be merged into this article or section. ...

Another used method is reverse osmosis. Reverse osmosis is the filtration process of hydraulically forcing a solvent through a filter that retains the solute on one side and allows the pure solvent to pass to the other side. ...

See also

• Double distilled water
• Hydrogen production

Double distilled water (abbreviated ddH2O or Bidest. ... Hydrogen production is done in bulk today from hydrocarbon fossil fuels via a chemical path. ...

External links

• Deionized Water (Physics Van QA Forum)