Freezing point constant table

The proportionality constants in these equations, fcb and kf, are called the moled boiling point constant and the moled freezing point constant, respectively. Their magnitudes depend on the nature of the solvent (Table 10.2). Note that when the solvent is water,... 

TABLE 8.8 Boiling-Point and Freezing-Point Constants... 

The constant kf is called the freezing-point constant of the solvent it is different for each solvent and must be determined experimentally (Table 8.8). The effect is quite small for instance, for a 0.1 m C12H220n(aq) (sucrose) solution,... 

Take the freezing-point constant from Table 8.8. 

By taking the freezing point constant for water as 1.86 from Table 9-3 and then substituting the values into the equation for freezing point depression, you obtain the change in freezing temperature ... 

Each solvent has its own characteristic freezing-point constant Kv and boiling-point constant Ab, the changes caused by 1 mole of solute in 1 kilogram of solvent. Selected constants are given in Table 21-1. 

Take the freezing-point constant from Table 8.9. Use this -molality to calculate the moles of solute in the sample by multiplying it by the mass of solvent in kilograms. At this stage, determine the molar mass of the solute by dividing the given mass of solute by the number of moles present. For the molecular formula, decide how many atoms of sulfur are needed in each molecule to account for the molar mass. 

The freezing-point constant, kf, depends on the solvent and has units of K-kg-mol (Table 8.8). -> The freezing-point depression equation holds for nonvolatile solutes in dilute solutions that are approximately ideal. 

The molar freezing-point constant for water has the value 1.86°C, the freezing point of a solution containing c moles of solute per 1000 g of water being —1.86 c in degrees C. For other solvents the values of this constant are shown in Table 9-1. 

Each solvent has its own characteristic molal freezing-point constant. The values of fy for some common solvents are given in Figure 2.3. These values are most accurate for dilute solutions at 1 atmosphere of pressure. Some variations are introduced in the value of fy at other pressures and with more-concentrated solutions. The table also shows the values of a related quantity called which you will study next. 

Table 23.1 Molal Boiling Point and Freezing Point Constants Substance T (°C) T C) K,...

The vapor pressure of pure benzene at 26°C is 1.00 X 10 mm Hg. Assume that the vapor pressure exerted by palmitic acid at 26°C is negligible. What is the vapor pressure of the solution at this temperature The normal boiling and freezing points of benzene and its boiling and freezing point constants can be found in Table 10.2. What is the normal boiling point and freezing point of this solution ... 

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

Constants and Chemical Properties. The constants of sulfur are presented in Table 1. Two freezing points ate given for each of the two crystalline modifications. When the Hquid phase consists solely of octatomic sulfur rings, the temperature ranges at which the various modifications form are called the ideal freezing points. The temperatures at which the crystalline forms are in equiHbtium with Hquid sulfur containing equiHbtium amounts of... 

The freezing point depression constant for water is known from experiments and can be found in tables Tf = 1.858 ° C kg/mol. To calculate the freezing point, we must first determine the molality of the... 

The fixed points in the ITS-90 are given in Table 11.39. Platinum resistance thermometers are recommended for use between 14 K and 1235 K (the freezing point of silver), calibrated against the fixed points. Below 14 K either the vapor pressure of helium or a constant-volume gas thermometer is to be used. Above 1235 K radiometry is to be used in conjunction with the Planck radiation law,... 

Table 5.3 Sample values of boiling and freezing points, and cryoscopic and ebullioscopic constants...

A great variety of aqueous—organic mixtures can be used. Most of them are listed in Table I with their respective freezing point and the temperature at which their bulk dielectric constant (D) equals that of pure water. These mixtures have physicochemical properties differing from those of an aqueous solution at normal temperature, but some of these differences can be compensated for. For example, the dielectric constant varies upon addition of cosolvent and cooling of the mixture in such a way that cooled mixed solvents can be prepared which keep D at is original value in water and are isodielectric with water at any selected temperature (Travers and Douzou, 1970, 1974). 

Table 17) whose temperature should be 2-3 °C below the freezing point of water. Watch the change in the temperature while constantly stirring the water with stirrer 2. 

PROBLEM 11.20 Assuming complete dissociation, what is the molality of an aqueous solution of KBr whose freezing point is —2.95°C The molal freezing-point-depression constant of water is given in Table 11.4. 

TABLE 2. Freezing-point depression and boiling-point elevation constants... 

Table 3.6 lists Kf and Kb for several solvents. In general, the higher the molar mass of the solvent, the larger the values of Kf and Kb. If the freezing point depression and boiling point elevation constants are known, the molecular weight of the dissolved solute, M2, can be determined ... 

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