Boiling point defined

Average boiling point defined as the mean of the temperatures in °C at which 10%, 20%,...90% by volume distills in a standard flask distillation. 

Strictly, the boiling temperature should be for 1 bar but the normal boiling point, defined for 1 atm, is commonly used and makes negligible difference. 

The choice of solvent is determined by several factors, including conductance, solubility of electrolyte and electroactive substance, and reactivity with electrolytic products. The solvent can also have important properties such as decreasing usually unwanted effects (e.g., adsorption of the electroactive species at the electrode). Because of the importance of the solvent in electrochemical processes, it is sometimes desirable to consider the physical and chemical properties of the solvent in some detail. Solvent properties relevant to electrochemical experiments are listed in Table 2-1. The melting and boiling points define the useful temperature range for most solvents (with some variation due... 

This is the ASTM D 2892 test method and corresponds to a laboratory technique defined for a distillation column having 15 to 18 theoretical plates and operating with a 5 1 reflux ratio. The test is commonly known as the TBP for True Boiling Point. 

Eleven different groups of crude oils haye been defined according to the densities of their heavy gasoline cuts (100-200°C) and their residues with boiling points above 350°C as shown in Table 3.1. 

From these observations, the characterization factor KfjQp (or was defined for pure components using only their boiling points and their densities , ... 

The vapour pressure of a liquid increases with rising temperature. A few typical vapour pressure curves are collected in Fig. 7,1, 1. When the vapour pressure becomes equal to the total pressure exerted on the surface of a liquid, the liquid boils, i.e., the liquid is vaporised by bubbles formed within the liquid. When the vapour pressure of the liquid is the same as the external pressure to which the liquid is subjected, the temperature does not, as a rale, rise further. If the supply of heat is increased, the rate at which bubbles are formed is increased and the heat of vaporisation is absorbed. The boiling point of a liquid may be defined as the temperature at which the vapour pressure of the liquid is equal to the external pressure dxerted at any point upon the liquid surface. This external pressure may be exerted by atmospheric air, by other gases, by vapour and air, etc. The boiling point at a pressure of 760 mm. of mercury, or one standard atmosphere, may be termed the normal boiling point. 

Acetylsalicylic acid decomposes when heated and does not possess a true, clearly-defined m.p. Decomposition points ranging from 128° to 135° have been recorded a value of 129-133° is obtained on an electric hot plate (Fig. II, 11, 1). Some decomposition may occur if the compound is recrystaUised from a solvent of high boiling point or if the boiling period during recrystallisation is unduly prolonged. 

Phosphorus(III) Oxide. Phosphoms(III) oxide [12440-00-5] the anhydride of phosphonic acid, is formed along with by-products such as phosphoms pentoxide and red phosphoms when phosphoms is burned with less than stoichiometric amounts of oxygen (62). Phosphoms(III) oxide is a poisonous, white, wax-like, crystalline material, which has a melting point of 23.8°C and a boiling point of 175.3°C. When added to hot water, phosphoms(III) oxide reacts violentiy and forms phosphine, phosphoric acid, and red phosphoms. Even in cold water, disproportionation maybe observed if the oxide is not well agitated, resulting in the formation of phosphoric acid and yellow or orange poorly defined polymeric lower oxides of phosphoms (LOOP). 

In the fire codes, the atmospheric boiling point is an important physical property used to classify the degree of hazardousness of a Hquid. If a mixture of Hquids is heated, it starts to bod at some temperature but continues to rise ia temperature over a boiling temperature range. Because the mixture does not have a definite boiling poiat, the NFPA fire codes define a comparable value of boiling poiat for the purposes of classifying Hquids. For petroleum mixture, it is based on the 10% poiat of a distillation performed ia accordance with ASTM D86, Standard Method of Test for Distillation of Petroleum Products. 

Capillary gc/ms, hplc, nmr, ir, and uv are all analytical methods used by the terpene chemist with a good Hbrary of reference spectra, capillary gc/ms is probably the most important method used in dealing with the more volatile terpenes used in the davor and fragrance industry (see Flavors and spices). The physical properties of density, refractive index, boiling point, melting point of derivatives, and specific rotation are used less frequendy but are important in defining product specifications. 

Extraction and Extractive Distillation. The choice of an extraction or extractive distillation solvent depends upon its boiling point, polarity, thermal stabiUty, selectivity, aromatics capacity, and upon the feed aromatic content (see Extraction). Capacity, defined as the quantity of material that is extracted from the feed by a given quantity of solvent, must be balanced against selectivity, defined as the degree to which the solvent extracts the aromatics in the feed in preference to paraffins and other materials. Most high capacity solvents have low selectivity. The ultimate choice of solvent is deterrnined by economics. The most important extraction processes use either sulfolane or glycols as the polar extraction solvent. 

The Kellogg and DePriester charts and their subsequent extensions and generahzations use the molar average boiling points of the liquid and vapor phases to represent the composition effect. An alternative measure of composition is the convergence pressure of the system, which is defined as that pressure at which the Kvalues for aU the components in an isothermal mixture converge to unity. It is analogous to the critical point for a pure component in the sense that the two... 

A term of great importance is relative volatility. Relative volatility is a measure of the differences in volatility between two components, and hence their boiling points. It indicates how easy or difficult a particular separation will be. The relative volatility of component i with, respect to component j is defined by the following relationship ... 

In crude distillation, there are thousands of different compounds present having a virtually continuous spectrum of boiling points. It would be impractical to consider each of these compounds in describing the crude or designing the equipment to process it. Instead the crude is treated as if it were composed of a manageable number (< 50) of pseudo components. These are defined by dividing the crude distillation curve into a series of adjacent boiling cuts. 

Boiling Point at 1 atm - Defined as the characteristic temperature of a liquid when its vapor pressure is 1 atm. As an example, when water is heated to 100°C (212°F), its vapor pressure rises to 1 atm and the liquid boils. The boiling point at 1 atm indicates whether the liquid will boil and become a gas at any particular temperature and at sea-level atmospheric pressure. 

The ability of a GC column to theoretically separate a multitude of components is normally defined by the capacity of the column. Component boiling point will be an initial property that determines relative component retention. Superimposed on this primary consideration is then the phase selectivity, which allows solutes of similar boiling point or volatility to be differentiated. In GC X GC, capacity is now defined in terms of the separation space available (11). As shown below, this space is an area determined by (a) the time of the modulation period (defined further below), which corresponds to an elution property on the second column, and (b) the elution time on the first column. In the normal experiment, the fast elution on the second column is conducted almost instantaneously, so will be essentially carried out under isothermal conditions, although the oven is temperature programmed. Thus, compounds will have an approximately constant peak width in the first dimension, but their widths in the second dimension will depend on how long they take to elute on the second column (isothermal conditions mean that later-eluting peaks on 2D are broader). In addition, peaks will have a variance (distribution) in each dimension depending on... 

Molal boiling point constant, 269,270t Molal freezing point constant, 269,270t Molality (m) A concentration unit defined as the number of moles of solute per kilogram of solvent, 259,261-262 Molar mass The mass of one mole of a substance, 55,68-68q alcohol, 591 alkane, 591... 

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