what is difference between deionised and distilled water?

Answer 1

The main difference is the way they are prepared. Deionized (deionised) water is passed through a column which bind ions in the water, replacing them with protons and hydroxide ions. It can't remove uncharged molecules from the source water. Distilled water is literally boiled and the vapors condensed back into liquid water. Some volatile contaminants in the water source can end up in the distilled water.

So each has the potential to remain contaminated, but with different kinds of things.

Answer 2

Double Distilled Water

Answer 3

distilled water doesot contains any impurities;where as deionised water doesnot contains any impurities as well as important ions which are essential to our body.deionised water is composed only of h+ and oh- ions.it is better to consume distilled water rather than deionised water

Answer 4

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.
[edit] 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.


[edit] 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 (Kw) ~ 10-14, so p[Kw] = 14, and pH + pOH = p[Kw].

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 a 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 cummulative. 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.


[edit] 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.


[edit] Uses
DI water is 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.

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 deionised water is in window cleaning, where window cleaners use pumped systems to brush and rinse windows with deionised water again without leaving any spots.

Deionized water is used in freshwater aquariums. Since it does not contain inpurities such as copper and chlorine, it keeps fishes 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.

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.


[edit] 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.Another used method is reverse osmosis.Distilled water is water that has virtually all of its impurities as well as electrolytes removed through distillation (boiling the water and re-condensing the steam into a clean container, leaving contaminants behind).
[edit] Applications
In chemical and biological laboratories, as well as industry, cheaper alternatives such as deionized water are preferred over distilled water. However, if these alternatives are not sufficiently pure, distilled water is used. Where exceptionally high purity water is required, double distilled water is used.

Distilled water is also commonly used to top up lead acid batteries used in cars and trucks. The presence of other ions commonly found in tap water will cause a drastic reduction in its lifespan.

Using distilled water in steam irons for pressing clothes can help reduce mineral build-up and make the iron last longer. However, many iron manufacturers say that distilled water is no longer necessary in their irons.[citation needed]

Some people use distilled water for household aquariums because it lacks the chemicals found in tap water supplies. It is important to supplement distilled water when using it for fishkeeping; it is too pure to sustain proper chemistry to support an aquarium ecosystem.


[edit] Drinking distilled water
Drinking distilled water is most common in ships, especially nuclear powered ones which require a large supply of distilled water as coolant. The water is produced by distilling seawater. Distilled water may also be used as drinking water in arid seaside areas which do not have sufficient freshwater, but plenty of seawater. The drinking water is produced in desalination plants, although it is very expensive due to the large amount of fuel needed to boil water. Alternative technologies, especially reverse osmosis are becoming increasingly important in this regard due to greatly reduced cost.

Distilled water is sometimes bottled and sold as well, especially where tap water is not suitable for consumption without boiling or chemical treatment. Some people drink distilled water for its purity and for its improved taste. Municipal water supplies may have trace contaminants at levels which are safe, but some people feel safer drinking distilled water. It also has no minerals, which may make it taste better.


[edit] Pros and cons
This section does not cite its references or sources.
Please help improve this article by introducing appropriate citations. (help, get involved!) This article has been tagged since June 2006.

The drinking of distilled water has been both advocated and discouraged for health reasons. The purported effect of drinking water in its pure form is a 'more powerful solvent' that helps cleanse toxins from the body. From a chemist's point of view, however, this statement is at best an incomplete description.

Detractors argue that it robs the body of essential minerals in this way and also deprives it of minerals normally acquired from drinking water. While there is no evidence to suggest that drinking distilled water is harmful or leaches minerals from the body, the World Health Organization has assembled considerable research which shows a relationship between drinking water containing naturally-occurring minerals and lower rates of certain diseases.[citation needed]

Despite the perceived benefits, the cost of distilling water (about 0.04 to 0.10 Euro or USD per litre in 2005) prohibits its use by most households worldwide.[citation needed]

It has been suggested that because distilled water (like reverse osmosis produced water) lacks fluoride ions that are added by many governments (such as most municipalities in the United States) at a water treatment plant for its effect on the inhibition of cavity formation, the drinking of distilled water may conceivably increase the risk of tooth decay due to a lack of this element.[1] Regardless, most people continue to cook with tap water as treated and delivered by their government, and in cases of fluoridized water this is thought to potentially provide sufficient fluoride to maintain normal prophylaxis in many cases. Studies funded by the World Health Organization and others seem to show a clear relationship between minerals in tap water such as calcium and magnesium and a decreased rate in certain diseases.

In many other developing countries, government water treatment is necessary for health, but distilled water, if affordable, can be even safer by eliminating risks caused by variations from standards. An argument against shunning distilled water for displacing government-treated water is that governments treat water because it is much more economical than individual households treating it. Therefore, people who can afford it may choose distilled water for their drinking, and that does not deprive them of an overall health and caries plan, nor does it deprive governments of making changes informed by new knowledge (such as providing a caries prevention plan that includes distilled drinking water).