Boiling point constants

The constants for liquids at the boiling-point (= constant divided by the speci/ic gravity of the solvent at the boiling-point) are as follows —... 

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,... 

Molal Freezing Point and Boiling Point Constants... 

Pure benzene boils at 80.10°C and has a boiling point constant, kb, of 2.53°CIm. A sample of benzene is contaminated by naphthalene, CioH8. The boiling point of the contaminated sample is 81.20°C. How pure is the sample (Express your answer as mass percent of benzene.)... 

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... 

Rearranging the boiling point equation to yield molality and substituting the molal boiling point constant from Table 9-3, you can derive the molality of the solution ... 

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. 

BOILING POINT CONSTANT. Consider a dilute solution in which all solulc species may be regarded as nonvolatile. The vapor in equilibrium with the solution is then formed from the solvent only. Call T° the boiling point of the pure solvent at the pressure concerned, and T the boiling point of the solution. For a dilute solution, the difference... 

Kbp is the molal boiling-point constant, a property of the solvent and independent of the nature of the solutes msolutes refers to the total concentration of independent solute particles whether they are neutral molecules or ions. Thus a 0.01 molal NaCl solution has a total solute con-... 

The molal boiling-point constant of the solvent is kb. As with kf, the numerical value is a property of the solvent alone and is independent of the solute, assuming a solute that is nonvolatile and a nonelectrolyte. Also assumed in the tables presenting kb values is that the pressure is 1 atm (standard pressure). 

A solution contains 10.6 g of a nonvolatile substance dissolved in 740 g of ether. The boiling point of the solution is 0.284°C over the boiling point of pure ether. Molal boiling-point constant for ether is 2.11°C kg/mol. What is the molar mass of the substance ... 

Elevation of Boiling Point. The boiling "point of a solution is higher than that of the pure solvent by an amount proportional to the iveight-molar concentration of the solute. Values of the proportionality factor, the molar boiling-point constant, are given below for some important solvents. 

SOLVENT BOILING POINT MOLAR f BOILING-POINT CONSTANT... 

Reasoning as in the preceding case we may establish without difficulty the following propositions When a liquid mixture is distilled whose inUiol composition Corresponds to a value of X less or greater than C, the boiling-point constantly rises and approaches 0 the composition of the liquid in the still and the composition of the vapor in it vary always in the same way, so as to approach the common composition f. 

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

A solution was made up by dissolving 3.75 g of a pure nonvolatile solute in 95 g of acetone. The boiling point of pure acetone was observed to be 55.95 °C, and of the solution, 56.50 °C. If the molal boiling-point constant of acetone is 1.71 °C kg/mol, what is the approximate molar mass of the solute ... 

---