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An energy profile of an exothermic reaction. In an exothermic reaction, by definition, the enthalpy change has a negative value: ΔH = H products - H reactants < 0. where a larger value (the higher energy of the reactants) is subtracted from a smaller value (the lower energy of the products). For example, when hydrogen burns: 2H 2 (g) + O 2 (g ...
The body temperatures of many small birds (e.g. hummingbirds) and small mammals (e.g. tenrecs) fall dramatically during daily inactivity, such as nightly in diurnal animals or during the day in nocturnal animals, thus reducing the energy cost of maintaining body temperature. Less drastic intermittent reduction in body temperature also occurs in ...
An exothermic thermite reaction using iron(III) oxide. The sparks flying outwards are globules of molten iron trailing smoke in their wake. Some examples of exothermic processes are: [14] Combustion of fuels such as wood, coal and oil/petroleum; The thermite reaction [15] The reaction of alkali metals and other highly electropositive metals ...
Simplified control circuit of human thermoregulation. [8]The core temperature of a human is regulated and stabilized primarily by the hypothalamus, a region of the brain linking the endocrine system to the nervous system, [9] and more specifically by the anterior hypothalamic nucleus and the adjacent preoptic area regions of the hypothalamus.
Such variation in body temperature is called poikilothermy, though the concept is not widely satisfactory and the use of the term is declining. In small aquatic creatures such as Rotifera , poikilothermy is practically absolute, but other creatures (like crabs ) have wider physiological options at their disposal, and they can move to preferred ...
The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. [1] Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix ...
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation.
Typical examples of exothermic reactions are combustion, precipitation and crystallization, in which ordered solids are formed from disordered gaseous or liquid phases. In contrast, in endothermic reactions, heat is consumed from the environment. This can occur by increasing the entropy of the system, often through the formation of gaseous or ...