Room temperature

Colloquially, room temperature is the range of air temperatures that most people prefer for indoor settings, which feel comfortable when wearing typical indoor clothing. Human comfort can extend beyond this range depending on humidity, air circulation and other factors. In certain fields, like science and engineering, and within a particular context, room temperature can mean different agreed-on ranges. In contrast, ambient temperature is the actual temperature of the air (or other medium and surroundings) in any particular place, as measured by a thermometer. It may be very different from usual room temperature, for example an unheated room in winter.

Mercury Thermometer
Mercury-in-glass thermometer showing an ambient temperature within the range of room temperature

Comfort levels

The American Heritage Dictionary of the English Language identifies room temperature as around 20 to 22 °C (68 to 72 °F),[1] while the Oxford English Dictionary states that it is "conventionally taken as about 20 °C (68 °F)".[2]

Owing to variations in humidity and likely clothing, recommendations for summer and winter may vary; a suggested typical range for summer is 23 to 25.5 °C (73 to 78 °F), with that for winter being 20 to 23.5 °C (68 to 74 °F),[3] although by other considerations the maximum should be below 24 °C (75 °F) – and to avoid sick building syndrome, below 22 °C (72 °F).[3]

Some studies have suggested that thermal comfort preferences of men and women may differ significantly, with women on average preferring higher ambient temperatures.[4][5][6]

The World Health Organization's standard for comfortable warmth is 18 °C (64 °F) for normal, healthy adults who are appropriately dressed. For those with respiratory problems or allergies, they recommend no less than 16 °C (61 °F), and for the sick, disabled, very old or very young, a minimum of 20 °C (68 °F).[7][8]

Definitions in science and industry

Temperature ranges are defined as room temperature for certain products and processes in industry, science, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines controlled room temperature as between 20 to 25 °C (68 to 77 °F), with excursions between 15 to 30 °C (59 to 86 °F) allowed, provided the mean kinetic temperature does not exceed 25 °C (77 °F).[9] The European Pharmacopoeia defines it as being simply 15 to 25 °C (59 to 77 °F), and the Japanese Pharmacopeia defines "ordinary temperature" as 15 to 25 °C (59 to 77 °F), with room temperature being 1 to 30 °C (34 to 86 °F).[10][11] Merriam-Webster gives as a medical definition a range of 15 to 25 °C (59 to 77 °F) as being suitable for human occupancy, and at which laboratory experiments are usually performed.[12]

Serving temperature of red wine

People traditionally serve red wine at room temperature. This practice dates from before central heating, when room temperature in wine-drinking countries was considerably lower than it is today, usually in the range between 15 °C (59 °F) and 18 °C (64 °F). The advice is therefore to serve the wine at, at most, about 18 °C (64 °F).[13]

See also

References

  1. ^ The American Heritage Dictionary of the English Language (5th ed.). 2014. Archived from the original on 2015-01-08.
  2. ^ Oxford English Dictionary, Third Edition, November 2010), sub-entry at room.
  3. ^ a b Burroughs, H. E.; Hansen, Shirley (2011). Managing Indoor Air Quality. Fairmont Press. pp. 149–151. Archived from the original on 20 September 2014. Retrieved 25 December 2014.
  4. ^ Beshir, MY; Ramsey, JD (March 1981). "Comparison between male and female subjective estimates of thermal effects and sensations". Applied Ergonomics. Retrieved Aug 30, 2018.
  5. ^ Karjalainen, Sami (April 2007). "Gender differences in thermal comfort and use of thermostats in everyday thermal environments". Building and Environment. Retrieved Aug 30, 2018.
  6. ^ Kingma, Boris; van Marken Lichtenbelt, Wouter (August 2015). "Energy consumption in buildings and female thermal demand". Nature Climate Change. Retrieved Aug 30, 2018.
  7. ^ "BBC News Magazine: How warm is your home". Archived from the original on 2017-12-31.
  8. ^ Karen Head, Mike Clarke, Meghan Bailey, Alicia Livinski, Ramona Ludolph, and Ambrish Singh. Report of the systematic review on the effect of indoor heat on health, WHO Housing and Health Guidelines. https://www.ncbi.nlm.nih.gov/books/NBK535282/
  9. ^ "General Chapter < 659> Packaging and Storage Requirements" (PDF). United States Pharmacopeia. 1 May 2017. Retrieved 2018-04-04.
  10. ^ "What are the regulatory Definitions for "Ambient", "Room Temperature" and "Cold Chain"?". ECA Academy. 2 March 2017. Retrieved 2018-04-04.
  11. ^ Shein-Chung Chow (2007). Statistical Design and Analysis of Stability Studies. Chapman & Hall/CRC Biostatistics Series. CRC Press. p. 7. ISBN 9781584889069. Retrieved 4 April 2018. 1.2.3.3 Definition of Room Temperature: According to the United States Pharmacopeia National Forumlary (USP-NF), the definition of room temperature is between 15 and 30 °C in the United States. However, in the EU, the room temperature is defined as being 15 to 25 °C, while in Japan, it is defined being 1 to 30 °C.
  12. ^ Merriam Webster's Medical Dictionary. 2016. Archived from the original on 2010-04-10.
  13. ^ Karen MacNeil (2015). The Wine Bible (revised second ed.). Workman Publishing. p. 130. ISBN 978-0-7611-8715-8.
Boukha

Boukha (Tunisian Arabic: بوخة‎) is a distilled beverage produced from figs. It originated in Tunisia, where most of it is still produced. Its name means 'alcohol vapor' in Judeo-Tunisian Arabic. It is obtained by simple distillation of Mediterranean figs. Its alcohol percentage ranges between 36 and 40 percent.

Boukha can be consumed straight at room temperature or cold, or serve as the basis for many cocktails and for fruit salad.

Butane

Butane () is an organic compound with the formula C4H10 that is an alkane with four carbon atoms. Butane is a gas at room temperature and atmospheric pressure. The term may refer to either of two structural isomers, n-butane or isobutane (also called "methylpropane"), or to a mixture of these isomers. In the IUPAC nomenclature, however, "butane" refers only to the n-butane isomer (which is the isomer with the unbranched structure). Butanes are highly flammable, colorless, easily liquefied gases that quickly vaporize at room temperature. The name butane comes from the roots but- (from butyric acid, named after the Greek word for butter) and -ane. It was discovered by the chemist Edward Frankland in 1849. It was found dissolved in crude petroleum in 1864 by Edmund Ronalds, who was the first to describe its properties.

Cheese pudding

Cheese pudding is a pudding made with cheese, which unlike cheesecake can be served at room temperature or frozen.

Chlorine perchlorate

Chlorine perchlorate is the chemical compound with the formula Cl2O4. This chlorine oxide is an asymmetric oxide, with one chlorine atom in oxidation state +1 and the other +7, with proper formula ClOClO3. It is produced by the photolysis of chlorine dioxide at room temperature with 436 nm ultraviolet light:

2 ClO2 → ClOClO3Chlorine perchlorate can also be made the following reactions at −45 °C.

CsClO4 + ClOSO2F → Cs(SO3)F + ClOClO3Chlorine perchlorate is a pale greenish liquid which decomposes at room temperature.

Cyclopropenone

Cyclopropenone is an organic compound with molecular formula C3H2O consisting of a cyclopropene carbon framework with a ketone functional group. It is a colorless, volatile liquid that boils near room temperature. Neat cyclopropenone polymerizes upon standing at room temperature. The chemical properties of the compound are dominated by the strong polarization of the carbonyl group, which gives a partial positive charge with aromatic stabilization on the ring and a partial negative charge on oxygen. It is an aromatic compound.

Fat

Fat is one of the three main macronutrients, along with carbohydrate and protein. Fats molecules consist of primarily carbon and hydrogen atoms, thus they are all hydrocarbon molecules. Examples include cholesterol, phospholipids and triglycerides.

The terms "lipid", "oil" and "fat" are often confused. "Lipid" is the general term, though a lipid is not necessarily a triglyceride. "Oil" normally refers to a lipid with short or unsaturated fatty acid chains that is liquid at room temperature, while "fat" (in the strict sense) specifically refers to lipids that are solids at room temperature – however, "fat" (in the broad sense) may be used in food science as a synonym for lipid. Fats, like other lipids, are generally hydrophobic, and are soluble in organic solvents and insoluble in water.

Fat is an important foodstuff for many forms of life, and fats serve both structural and metabolic functions. They are a necessary part of the diet of most heterotrophs (including humans) and are the most energy dense, thus the most efficient form of energy storage.Some fatty acids that are set free by the digestion of fats are called essential because they cannot be synthesized in the body from simpler constituents. There are two essential fatty acids (EFAs) in human nutrition: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). Other lipids needed by the body can be synthesized from these and other fats. Fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas.

Fats and oils are categorized according to the number and bonding of the carbon atoms in the aliphatic chain. Fats that are saturated fats have no double bonds between the carbons in the chain. Unsaturated fats have one or more double bonded carbons in the chain. The nomenclature is based on the non-acid (non-carbonyl) end of the chain. This end is called the omega end or the n-end. Thus alpha-linolenic acid is called an omega-3 fatty acid because the 3rd carbon from that end is the first double bonded carbon in the chain counting from that end. Some oils and fats have multiple double bonds and are therefore called polyunsaturated fats. Unsaturated fats can be further divided into cis fats, which are the most common in nature, and trans fats, which are rare in nature. Unsaturated fats can be altered by reaction with hydrogen effected by a catalyst. This action, called hydrogenation, tends to break all the double bonds and makes a fully saturated fat. To make vegetable shortening, then, liquid cis-unsaturated fats such as vegetable oils are hydrogenated to produce saturated fats, which have more desirable physical properties e.g., they melt at a desirable temperature (30–40 °C), and store well, whereas polyunsaturated oils go rancid when they react with oxygen in the air. However, trans fats are generated during hydrogenation as contaminants created by an unwanted side reaction on the catalyst during partial hydrogenation.

Saturated fats can stack themselves in a closely packed arrangement, so they can solidify easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids. Olive and linseed oils on the other hand are unsaturated and liquid. Fats serve both as energy sources for the body, and as stores for energy in excess of what the body needs immediately. Each gram of fat when burned or metabolized releases about 9 food calories (37 kJ = 8.8 kcal). Fats are broken down in the healthy body to release their constituents, glycerol and fatty acids. Glycerol itself can be converted to glucose by the liver and so become a source of energy.

Ionic liquid

An ionic liquid (IL) is a salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below some arbitrary temperature, such as 100 °C (212 °F). While ordinary liquids such as water and gasoline are predominantly made of electrically neutral molecules, ionic liquids are largely made of ions and short-lived ion pairs. These substances are variously called liquid electrolytes, ionic melts, ionic fluids, fused salts, liquid salts, or ionic glasses.

They are known as "solvents of the future" as well as "designer solvents".Ionic liquids are described as having many potential applications. They are powerful solvents and electrically conducting fluids (electrolytes). Salts that are liquid at near-ambient temperature are important for electric battery applications, and have been considered as sealants due to their very low vapor pressure.

Any salt that melts without decomposing or vaporizing usually yields an ionic liquid. Sodium chloride (NaCl), for example, melts at 801 °C (1,474 °F) into a liquid that consists largely of sodium cations (Na+) and chloride anions (Cl−). Conversely, when an ionic liquid is cooled, it often forms an ionic solid—which may be either crystalline or glassy.

The ionic bond is usually stronger than the Van der Waals forces between the molecules of ordinary liquids. For that reason, common salts tend to melt at higher temperatures than other solid molecules. Some salts are liquid at or below room temperature. Examples include compounds based on the 1-Ethyl-3-methylimidazolium (EMIM) cation and include: EMIM:Cl, EMIM dicyanamide, (C2H5)(CH3)C3H3N+2·N(CN)−2, that melts at −21 °C (−6 °F); and 1-butyl-3,5-dimethylpyridinium bromide which becomes a glass below −24 °C (−11 °F).Low-temperature ionic liquids can be compared to ionic solutions, liquids that contain both ions and neutral molecules, and in particular to the so-called deep eutectic solvents, mixtures of ionic and non-ionic solid substances which have much lower melting points than the pure compounds. Certain mixtures of nitrate salts can have melting points below 100 °C.The term "ionic liquid" in the general sense was used as early as 1943.

When Tawny crazy ants (Nylanderia fulva) combat Fire ants (Solenopsis invicta), the latter spray them with a toxic, lipophilic, alkaloid-based venom. The Tawny crazy ant then exudes its own venom, formic acid, and self-grooms with it, an action which de-toxifies the Fire ant venom. The mixed venoms chemically react with one another to form an ionic liquid, the first naturally occurring IL to be described.

Magnetic refrigeration

Magnetic refrigeration is a cooling technology based on the magnetocaloric effect. This technique can be used to attain extremely low temperatures, as well as the ranges used in common refrigerators.The effect was first observed by a German physicist Warburg (1881) Subsequently by French physicist P. Weiss and Swiss physicist A. Piccard in 1917. The fundamental principle was suggested by P. Debye (1926) and W. Giauque (1927). The first working magnetic refrigerators were constructed by several groups beginning in 1933. Magnetic refrigeration was the first method developed for cooling below about 0.3K (a temperature attainable by 3He refrigeration, that is pumping on the 3He vapors).

Muon-catalyzed fusion

Muon-catalyzed fusion (μCF) is a process allowing nuclear fusion to take place at temperatures significantly lower than the temperatures required for thermonuclear fusion, even at room temperature or lower. It is one of the few known ways of catalyzing nuclear fusion reactions.

Muons are unstable subatomic particles. They are similar to electrons, but are about 207 times more massive. If a muon replaces one of the electrons in a hydrogen molecule, the nuclei are consequently drawn 196 times closer than in a normal molecule, due to the reduced mass being 196 times the mass of an electron. When the nuclei are this close together, the probability of nuclear fusion is greatly increased, to the point where a significant number of fusion events can happen at room temperature.

Current techniques for creating large numbers of muons require far more energy than would be produced by the resulting catalyzed nuclear fusion reactions. Moreover, each muon has about a 1% chance of "sticking" to the alpha particle produced by the nuclear fusion of a deuteron with a triton, removing the "stuck" muon from the catalytic cycle, meaning that each muon can only catalyze at most a few hundred deuterium tritium nuclear fusion reactions. These two factors prevent muon-catalyzed fusion from becoming a practical power source, limiting it to a laboratory curiosity. To create useful room-temperature muon-catalyzed fusion, reactors would need a cheaper, more efficient muon source and/or a way for each individual muon to catalyze many more fusion reactions.

Room-temperature superconductor

A room-temperature superconductor is a material that is capable of exhibiting superconductivity at operating temperatures above 0 °C (273.15 K). While this is not strictly "room temperature", which would be approximately 20–25 °C, it is the temperature at which ice forms and can be reached and easily maintained in an everyday environment. In February 2019, US Navy filed a patent claiming that a room-temperature superconductivity can be achieved using a wire with an insulator core and an aluminum lead zirconate titanate. Another high temperature superconducting material is highly pressurized hydrogen sulfide, the transition temperature of which is 203 K (−70 °C), the highest accepted superconducting critical temperature as of 2015. By substituting a small part of sulfur with phosphorus and using even higher pressures, it has been predicted that it may be possible to raise the critical temperature to above 0 °C and achieve room-temperature superconductivity. Previously the record was held by the cuprates, which have demonstrated superconductivity at atmospheric pressure at temperatures as high as 138 K (−135 °C), and 164 K (−109 °C) under high pressure.Although some researchers doubt whether room-temperature superconductivity is actually achievable, superconductivity has repeatedly been discovered at temperatures that were previously unexpected or held to be impossible.

Claims of "near-room temperature" transient effects date from the early 1950s and some suggest that in fact the breakthrough might have been made more than once but could not be made stable enough and/or reproducible as the relationship between isotope number and Tc was not known at the time.

Finding a room temperature superconductor "would have enormous technological importance and, for example, help to solve the world’s energy problems, provide for faster computers, allow for novel memory-storage devices, and enable ultra-sensitive sensors, among many other possibilities."

Shortening

Shortening is any fat that is a solid at room temperature and used to make crumbly pastry and other food products. Although butter is solid at room temperature and is frequently used in making pastry, the term "shortening" seldom refers to butter, but is more closely related to margarine.

Speeds of sound of the elements

The speed of sound in any chemical element in the fluid phase has one temperature-dependent value. In the solid phase, different types of sound wave may be propagated, each with its own speed: among these types of wave are longitudinal (as in fluids), transversal, and (along a surface or plate) extensional.

Standard molar entropy

In chemistry, the standard molar entropy is the entropy content of one mole of substance under a standard state (not STP).

The standard molar entropy is usually given the symbol S°, and has units of joules per mole kelvin (J mol−1 K−1). Unlike standard enthalpies of formation, the value of S° is absolute. That is, an element in its standard state has a definite, nonzero value of S at room temperature. The entropy of a pure crystalline structure can be 0 J mol−1 K−1 only at 0 K, according to the third law of thermodynamics. However, this presupposes that the material forms a 'perfect crystal' without any frozen in entropy (defects, dislocations), which is never completely true because crystals always grow at a finite temperature. However this residual entropy is often quite negligible.

Triglyceride

A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from tri- and glyceride). Triglycerides are the main constituents of body fat in humans and other animals, as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, and are a major component of human skin oils.There are many different types of triglyceride, with the main division between saturated and unsaturated types. Saturated fats are "saturated" with hydrogen — all available places where hydrogen atoms could be bonded to carbon atoms are occupied. These have a higher melting point and are more likely to be solid at room temperature. Unsaturated fats have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. These have a lower melting point and are more likely to be liquid at room temperature.

Vulcanization

Vulcanization (British: vulcanisation) is a chemical process, invented by Charles Goodyear, used to harden rubber. Vulcanization traditionally referred to the treatment of natural rubber with sulfur and this remains the most common example, however the term has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides.

Vulcanization can therefore be defined as the curing of elastomers; with the terms 'vulcanization' and 'curing' sometimes used interchangeably in this context. It works by forming cross-links between sections of polymer chain which results in increased rigidity and durability, as well as other changes in the mechanical and electrical properties of the material. Vulcanization, in common with the curing of other thermosetting polymers, is generally irreversible.

The word vulcanization is derived from Vulcan, the Roman god of fire.

White chocolate

White chocolate is a chocolate confection made from cocoa butter, sugar and milk solids. It lacks the cocoa solids found in other types of chocolate. It is characterized by a pale ivory color. The melting point of cocoa butter, the only cocoa bean component of white chocolate, is high enough to keep white chocolate solid at room temperature, as with milk chocolate or dark chocolate.

Zinc oxide

Zinc oxide is an inorganic compound with the formula ZnO. ZnO is a white powder that is insoluble in water, and it is widely used as an additive in numerous materials and products including rubbers, plastics, ceramics, glass, cement, lubricants, paints, ointments, adhesives, sealants, pigments, foods, batteries, ferrites, fire retardants, and first-aid tapes. Although it occurs naturally as the mineral zincite, most zinc oxide is produced synthetically.ZnO is a wide-bandgap semiconductor of the II-VI semiconductor group. The native doping of the semiconductor due to oxygen vacancies or zinc interstitials is n-type. This semiconductor has several favorable properties, including good transparency, high electron mobility, wide bandgap, and strong room-temperature luminescence. Those properties are valuable in emerging applications for: transparent electrodes in liquid crystal displays, energy-saving or heat-protecting windows, and electronics as thin-film transistors and light-emitting diodes.

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