Dehydrasjon

Dehydrasjon is a term used to describe the state or process of removing water. In everyday usage it commonly refers to dehydration in biological contexts, while in chemistry it describes reactions that remove water from a substrate. The word derives from Greek hydor (water) and a- (without).

Physiological dehydration occurs when the body loses more water than it takes in. Causes include inadequate fluid intake, heavy sweating, fever, vomiting or diarrhea, and certain medicines such as diuretics. Early symptoms are thirst, dry mouth, reduced urination, and dark urine. With progression, skin becomes dry, mucous membranes falter, lightheadedness or dizziness appears, and mental function may be affected in the elderly or in children. Severe dehydration is a medical emergency and can lead to shock, rapid heartbeat, and organ dysfunction.

Chemical dehydration is the removal of water from a molecule or compound. In organic chemistry, dehydration reactions form new bonds and release water, such as the conversion of ethanol to ethene under acid catalysis. In biology, dehydration synthesis links monomers to polymers with water elimination. In inorganic settings, water is removed from hydrates or hydrated salts by heating or drying agents, producing oxides or anhydrous salts. Common catalysts include concentrated sulfuric acid or alumina. Dehydration also occurs in industrial processes such as the dehydration of alcohols, the production of waxes, and the processing of some acids.

Etymology: from Greek hydor "water" and suffix -osis denoting a condition.