Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. Inorganic chemistry is the branch of Chemistry concerned with the properties and behavior of Inorganic compounds This field covers all Chemical compounds Organic chemistry is a discipline within Chemistry which involves the scientific study of the structure properties composition reactions, and preparation Water is a common Chemical substance that is essential for the survival of all known forms of Life. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood.

A man hydrates his body by drinking water.

Chemical nature of hydrates

In organic chemistry, a hydrate is a compound formed by the addition of water or its elements to a host molecule. Water is a common Chemical substance that is essential for the survival of all known forms of Life. For example, ethanol, CH₃—CH₂—OH, can be considered as a hydrate of ethylene, CH₂=CH₂, formed by the addition of H to one C and OH to the other C. A molecule of water may be eliminated, for example by the action of sulfuric acid. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Another example is chloral hydrate, CCl₃—CH(OH)₂, which can be formed by reaction of water with chloral, CCl₃—CH=O. Chloral hydrate is a Sedative and Hypnotic drug as well as a Chemical reagent and precursor Chloral, also known as trichloroacetaldehyde is the Organic compound with the formula Cl3CCHO

Other molecules have been labeled as hydrates for historical reasons. Glucose, C₆H₁₂O₆, was originally thought of as C₆(H₂O)₆ and described as a carbohydrate, but this is a very poor description of its structure as known today. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. And methanol is often sold as “methyl hydrate”, implying an incorrect formula CH₃OH₂, although the correct formula is CH₃—OH. Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound

In inorganic chemistry, hydrates contain water molecules that are either bound to a metal center or crystallized with the metal complex. Such hydrates are also said to contain "water of crystallization" or "water of hydration". Water of crystallization (alt BrE water of crystallisation is Water that occurs in Crystals but is not covalently bonded to a host Molecule If the water is heavy water, where the hydrogen consists of the isotope deuterium, then the term deuterate may be used in place of hydrate. Heavy water is water which contains a higher proportion than normal of the Isotope Deuterium, as deuterium oxide, D2O or ²H2O Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Deuterium, also called heavy hydrogen, is a Stable isotope of Hydrogen with a Natural abundance in the Oceans of Earth

Anhydrous Cobalt(II) chloride CoCl₂

Cobalt(II) chloride hexahydrate Co(H₂O)₆Cl₂

A colorful example is cobalt(II) chloride, which turns from blue to magenta (red) upon hydration, and can therefore be used as a water indicator. Cobalt(II chloride is the Chemical compound with the formula Co[[chlorine Cl2]] although the term is used also to refer to the hexahydrate which Mineral hydration is an inorganic chemical reaction where water is added to the Crystal structure of a Mineral, usually creating a new mineral usually called a

The notation of hydrous compound · nH₂O, where n is the number of water molecules per molecule of salt, is commonly used to show that a salt is hydrated. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The n is usually a low integer, though it is possible for fractional values to exist. The integers (from the Latin integer, literally "untouched" hence "whole" the word entire comes from the same origin but via French In a monohydrate n is one, in a hexahydrate n is 6 etc. Such water is also referred to as water of crystallization. Water of crystallization (alt BrE water of crystallisation is Water that occurs in Crystals but is not covalently bonded to a host Molecule Examples include borax decahydrate, clathrate hydrates (a class of solid hydrates of gases), and chalcanthite. Borax (from Persian burah) also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important Boron Clathrate hydrates (or gas clathrates gas hydrates clathrates hydrates etc were first documented in 1810 by Sir Humphrey Davy; they are crystalline Chalcanthite, whose name derives from the Greek chalkos and anthos, meaning copper flower is a richly-colored blue/green water-soluble Sulfate Gas hydrates are clathrate hydrates: water ice with gas molecules trapped within. Clathrate hydrates (or gas clathrates gas hydrates clathrates hydrates etc were first documented in 1810 by Sir Humphrey Davy; they are crystalline When the gas is methane it is called a methane hydrate. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Methane clathrate, also called methane hydrate or methane ice, is a solid form of water that contains a large amount of Methane within its Crystal

A hydrate which has lost water is referred to as an anhydride, and can normally lose further water only upon strong heating, if at all. In Chemistry, an anhydride is a compound that can be considered as derived from another compound by subtracting the molecules of water. A substance which contains no water is referred to as anhydrous. As a general term a substance is said to be anhydrous if it contains no Water.

Applications of hydrates

Construction

The presence of hydrates is quite purposeful in the three fields of endeavour. Generally, in construction and refractories, inorganic binders are often deprived of water during manufacture. In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure A refractory is a material that retains its strength at high Temperatures ASTM C71 defines refractories as "non-metallic materials having those chemical and physical For instance, both in cement and gypsum products, heat is applied to the raw materials. In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together Gypsum is a very soft Mineral composed of Calcium sulfate dihydrate with the Chemical formula Ca[[sulfur S]] O 4·2 In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Once water is added on a construction site, the powder is re-hydrated and able to form bonds with other substances that are present. Thus, one goes from powder, to slurry, or paste and then forms "cement stone". Water that is not chemically bound, or converted into hydrates, can come off again as steam, especially due to the heat of hydration, with cement products in particular, which undergo an exothermic chemical reaction with water. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. In Thermodynamics, the word exothermic "outside heating" describes a process or reaction that releases Energy usually in the form of Heat, but

Generally, the longer one can keep cementitious products wet immediately after placement, the better. The wetter cementitious products are kept, the more water will be converted into hydrates, instead of evaporating off due to the heat of hydration and other environmental influences. Premature drying is a cause for severe concrete problems, such as cracking and shrinking.

Passive fire protection (PFP)

Avoiding premature drying is important to all other cementitious building products, particularly spray fireproofing and firestop mortars, where the slightest cracking can lead to rejection. "Fireproof" redirects here For the album see Fireproof (album. A firestop is a Passive fire protection System of various components used to seal openings and joints in fire-resistance rated wall The chemically bound water is used up by endothermic reactions when exposed to the heat of a fire. In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. Fire temperatures in a building can reach 1100°C, depending on the fuel present and the availability of oxygen, but the hydrates keep the temperature of the item at or below 100 °C until all the water is spent. In Architecture, Construction, Engineering and real estate development the word building may refer to one of the following Any man-made Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Therefore, the more hydrates, the longer the fire-resistance duration. This is what lends fire-resistive characteristics to basic, or "old" building materials, like gypsum, concrete or plaster. For other kinds of building materials see Hardware, Biology, Star formation. Gypsum is a very soft Mineral composed of Calcium sulfate dihydrate with the Chemical formula Ca[[sulfur S]] O 4·2 Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag The term plaster can refer to plaster of Paris Lime plaster, or Cement plaster.

Fire-resistance duration is important to many high-tech PFP products such as intumescent and endothermic paints, wraps and tiles, such as those used in space physics for re-entry vehicles. An intumescent is a substance which swells as a result of Heat exposure thus increasing in Volume, and decreasing in Density. Space physics, also known as space plasma physics, is the study of plasmas as they occur naturally in the Universe.

See also

• Passive fire protection