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A salt with associated water of crystallization is known as a hydrate. The structure of hydrates can be quite elaborate, because of the existence of hydrogen bonds that define polymeric structures. [ 3 ] [ 4 ] Historically, the structures of many hydrates were unknown, and the dot in the formula of a hydrate was employed to specify the ...
Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, cooling rate, and in the case of liquid crystals, time of fluid evaporation. Crystallization occurs in two major steps.
C 4 AF hydrates as hydrogarnet and ferrous ettringite. Sulfate attack typically happens to ground floor slabs in contact with soils containing a source of sulfates. [2] Sulfates dissolved by ground moisture migrate into the concrete of the slab where they react with different mineral phases of the hardened cement paste.
In inorganic chemistry, mineral hydration is a reaction which adds water to the crystal structure of a mineral, usually creating a new mineral, commonly called a hydrate.. In geological terms, the process of mineral hydration is known as retrograde alteration and is a process occurring in retrograde metamorphism.
Protein crystals commonly have as much as 50% water content. Molecules are also labeled as hydrates for historical reasons not covered above. Glucose, C 6 H 12 O 6, was originally thought of as C 6 (H 2 O) 6 and described as a carbohydrate. Hydrate formation is common for active ingredients. Many manufacturing processes provide an opportunity ...
Clathrate hydrate, which encaged CO 2 as guest molecule is termed as CO 2 hydrate. The term CO 2 hydrates are more commonly used these days with its relevance in anthropogenic CO 2 capture and sequestration. A nonstoichiometric compound, carbon dioxide hydrate, is composed of hydrogen-bonded water molecules arranged in ice-like frameworks that ...
Aldehydes and to some extent even ketones, hydrate to geminal diols. The reaction is especially dominant for formaldehyde, which, in the presence of water, exists significantly as dihydroxymethane. Conceptually similar reactions include hydroamination and hydroalkoxylation, which involve adding amines and alcohols to alkenes.
This reaction is expansive and can cause a huge crystallization pressure in the small concrete pores once they are totally filled by the growing ettringite crystals. [23] As a consequence, the hardened cement paste (HCP) is submitted to an important tensile stress and starts to crack because of the internal expansion of the concrete matrix.