Constant cryoscopic

TABLE 11.2 Molecular Lowering of the Melting or Freezing Point Cryoscopic constants. 

The cryoscopic constant Kj gives the depression of the melting point AT (in degrees Celsius) produced when 1 mol of solute is dissolved in 1000 g of a solvent. It is applicable only to dilute solutions for which the number of moles of solute is negligible in comparison with the number of moles of solvent. It is often used for molecular weight determinations. 

The cryoscopic constant of sulfuric acid can be estimated from actual measurements with solutes assumed to be entirely in some particular state of ionization, or it can be calculated from the heat of... 

SAQ 5.6 Pure water has a normal freezing point of 273.15 K. What will be the new normal freezing point of water if 11 g of KCI is dissolved in 0.9 dm3 of water The cryoscopic constant of water is 1.86 Kkg-1 mol-1 assume the density of water is 1 gem-3, i.e. molality and molarity are the same. 

Camphor has a very high cryoscopic constant and its melting point is very greatly depressed by substances dissolved in it. The depression is about 8 times as great as that in benzene. Ebenzene = 5-1, Eoamphor = 40. This means that a molar solution in camphor melts 40° lower than the solvent, i.e. than camphor itself. Accordingly, even with relatively dilute camphor solutions the depressions obtained are so great that the sensitivity of an ordinary thermometer (which can be read to 0-25°) suffices completely for the determination.2... 

Frandsen, M. Cryoscopic constant, heat of fusion, and heat capacity of camphor. Bur. Stand. J. Res., 7 477-483, 1931. 

Golovanova, Yu.G. and Kolesov, V.P. Enthalpies of melting, melting temperatures, and cryoscopic constants of some haloorganic compounds, Vestn. Mosk Univ, Ser. 2 Khlm, 25(3) 244-248, 1984. 

This value relates to the pure crystalline ester, and to discuss bond dissociation energies it is necessary to have a value for the heat of formation of gaseous phenyl benzoate. The latent heat of sublimation at 25 °C. may be derived from separate values for fusion and vaporization. We have measured the latent heats of fusion at 70 °C. as AHfus = 7.0 0.3 kcal. per mole (both electrically and from determining the cryoscopic constant). An average value of the latent heat of vaporization, AHvap = 14.2 0.2 kcal. per mole, may be evaluated from existing (17) vapor... 

The standard processes of fractionation used in this work are distillation, extraction, adsorption, and crystallization, which involve the properties of vapor pressure (or boiling point), solubility, adsorbability, and freezing point (and cryoscopic constant). These processes of fractionation may be used in several variations ... 

Cryoscopic Constants, A0, B° Cryoscopic constants for calculating mole °U purity. See /. Research Natl. Bur. Standards, 35 (1945) RP 1676. 

CRYOSCOPIC CONSTANT. A quantity calculated to represent the mofal depression of the freezing point of a solution, by the relationship... 

In Table 4.9A, a range of compounds and their cryoscopic constants are recorded. All of the same data are included in Table 4.9B but they are rearranged in order of increasing melting point at the left and decreasing Kf at the right. 

You dissolve 90 g of sucrose (molar mass = 342 g/mol) in 1000 g of water. What is the molality of the solution If the cryoscopic constant for water is 1.9 degrees/molal, what is the freezing point of the solution ... 

The cryoscopic constant of the cryolite is 25.31 therefore, for each mole of foreign ions added to 1 kg cryolite, the cryolite liquidus temperature decreases... 

One-fifth mole of a weak monobasic acid is dissolved in 1000 cc of water (cryoscopic constant 1.86 degrees). The freezing point of the resulting solution is —0.396 degrees. Calculate for the acid. 

If the latent heat of fusion is taken as 5-0 calories absorbed per gram of phosphorus at the melting-point (Tm = 317-5° C. (abs.)), the high value of 40-4 is obtained as the cryoscopic constant for 1 mol of a solute in 1000 grams of phosphorus. The experimental value obtained by dissolving naphthalene in phosphorus was 33-2.5... 

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