Freezing point of mixtures

Existence of other Bromides.—At one time the existence of compounds SBr2 and SBr4 was suspected, but the evidence is insufficient and unconvincing.1 The curves representing the vapour pressures and the freezing-points of mixtures of sulphur monobromide and bromine give no indication of the formation of any compound. The evidence thus supplied merely indicates that neither dibromide nor tetrabromide is formed on mixing the monobromide and bromine.2... 

Fig. 50.—The Freezing Points of Mixtures of Potassium and Sodium Amides.

In this laboratory, Travers and Douzou (1970, 1974) measured D as a function of the volume ratio at constant temperature of various aqueous-organic mixtures, and then for selected volume ratios as a function of temperature between room temperature and the freezing point of mixtures. The results are reported in Tables IV—XI and in Fig. 5. 

Examples.—On determining the freezing-points of mixtures of phenol and a-naphthylamine, a curve (Fig. 39) is obtained of the type shown in Fig. 37, curve L, indicating the formation of a compound. ... 

Uquidus curve The freezing point of a molten mixture of substances varies with the composition of the mixture. If the freezing points are plotted as a function of the composition, the line joining the points is called a liquidus curve. Such mixtures usually freeze over a range of temperature. If the temperature at which the last traces of liquid just solidify (assuming that sufficient time has been allowed for equilibrium to be established) are plotted against composition the resulting line is called a solidus curve. 

Then again remove T, and drop a weighed pellet of the solute through the side arm A. Stir the mixture until a clear solution is obtained, and then repeat the above process until three consistent readings of the freezing point of the solution have been obtained. Then add a second weighed pellet of the solute, and determine the freezing-p>oint of this more concentrated solution in the same way. 

System in which the solid phases consist of the pure components and the components are completely miscible in the liquid phase. We may now conveniently consider the general case of a system in which the two components A and B are completely miscible in the liquid state and the solid phases consist of the pure components. The equilibrium diagram is shown in Fig. 1,12, 1. Here the points A and B are the melting points of the pure components A and B respectively. If the freezing points of a series of liquid mixtures, varying in composition from pure A to pure B, are determined, the two curves represented by AC and BC will be obtained. The curve AC expresses the compositions of solutions which are in equilibrium, at different temperatures, with the solid component A, and, likewise, the curve BC denotes the compositions... 

When freshly exposed to air, thallium exhibits a metallic luster, but soon develops a bluish-gray tinge, resembling lead in appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydride is formed. The metal is very soft and malleable. It can be cut with a knife. Twenty five isotopic forms of thallium, with atomic masses ranging from 184 to 210 are recognized. Natural thallium is a mixture of two isotopes. A mercury-thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at -60C, some 20 degrees below the freezing point of mercury. 

Freezing point of ethyl alcohol-water mixtures ... 

Many chemicals when added to water cause a freezing point depression, as shown in Table 1, and thus are termed antifreezes. The antifreeze properties of these chemicals vary widely as a function of their coUigative, or concentrative, properties. The reduction in freeze point depends both on the chemical itself and the concentration of the chemical in water. The freeze point depression increases as the antifreeze chemical is added to the water, until a characteristic concentration is achieved. Further addition of the antifreeze chemical to water will either result in insolubility or serve to increase the freezing point of the mixture, as illustrated in Figure 1. 

Percentage of Cineol in Mixture. Freezing-points. Terpene Mixture. Freezing-points. Sesquiterpene Mixture.. ... 

The specific enthalpy (or total heat) of the mixture can be taken from 0 K (- 273.15°C) or from any convenient arbitrary zero. Since most air-conditioning processes take place above the freezing point of water, and we are concerned mostly with differences rather than absolute values, this is commonly taken as 0°C, dry air. For conditions of 25°C, saturated, the specific enthalpy of the mixture, per kilogram of dry air, is... 

An antifreeze solution is prepared containing 50.0 cm3 of ethylene glycol, C2H602 (d = 1.12 g/cm3), in 50.0 g of water. Calculate the freezing point of this 50-50 mixture. 

When 13.66 g of lactic acid, C3H603j is mixed with 115 g of stearic acid, the mixture freezes at 62.7°C. The freezing point of pure stearic acid is 69.4°C. What is the freezing point constant of stearic acid ... 

The Rast method uses camphor (Ci0Hi O) as a solvent for determining the molar mass of a compound. When 2.50 g of cortisone acetate is dissolved in 50.00 g of camphor (kf = 40.0°C/m), the freezing point of the mixture is determined to be 173.44°C that of pure camphor is 178.40°C. What is the molar mass of cortisone acetate ... 

C14-0008. Suppose that a mixture of ice and water is placed in a refrigerator that is held at the freezing point of water, exactly 0.0 °C. Calculate A S for the ice-water mixture, A S for the refrigerator, and A Stgtai when 5.00 g of ice forms. Is this process spontaneous Is the reverse process spontaneous ... 

An antifreeze is defined as an additive that, when added to a water-based fluid, will reduce the freezing point of the mixture [1671]. Antifreezes are used in mechanical equipment in environments below the freezing point to prevent the freezing of heat-transfer fluids. Another field of application is in cementing jobs to allow operation below the freezing point. 

Mixtures of aqueous emulsions of oil can be more effectively transported through pipelines if certain antifreeze formulations are added to the system. Stable oil-in-water emulsions for pipeline transmission by using 0.05% to 4% ethoxylated alkylphenol as an emulgator and a freezing-point depressant for water enable pipeline transmission at temperatures below the freezing point of water [736]. 

As illustrated in Figure 12, the reaction mixture contains mono-, di-, and tri-brominated glycols, hydrobromic acid, and water. The mixture is extremely corrosive, and the reactor is operated at a temperature just above the freezing point of the product. The key to successfully sampling this mixture was the use of a corrosion-resistant tantalum sampling system. In addition, the sample line was continuously flushed with reactor solvent except during sampling. 

T is bis-(2-chloroethylthio)ethyl ether. It is a byproduct of certain methods of mustard manufacture, and is intentionally included in certain munitions to depress the freezing point of the mustard. T is also a vesicant the toxicology and the chemistry of T are quite similar to the corresponding properties of mustard. Mustard T accounts for 40% of HT mixture. 

Celsius (°C) A scale for measuring temperatures, also known as the centigrade scale, where the freezing point of water is 0°C and the boiling point 100°C. cement A natural or artificial fluid or semifluid substance, or mixture of substances, that hardens to act as an adhesive for binding solid surfaces together, cement, hydraulic A type of waterproof stony cement that sets even under water see pozzolana. 

---