Molality Molar boiling-point constant

Given (a) the mass of solute and solvent in a solution (b) the freezing-point depression or hoiling-point elevation, or data from which they may be found and (c) the molal freezing/boiling-point constant of the solvent, find the approximate molar mass of the solute. 

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... 

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 ... 

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 ... 

A solution contains 3.75 g of a nonvolatile pure hydrocarbon in 95 g acetone. The boiling points of pure acetone and the solution are 55.95X and 56.50X, respectively. The molal boiling-point constant of acetone is 1.71X kg/mol. What is the molar mass of the hydrocarbon ... 

A compound called pyrene has the empirical formula CgHg. When 4.04 g of pyrene is dissolved in 10.00 g of benzene, the boiling point of the solution is 85.rc. Calculate the molar mass of pyrene and determine its molecular formula. The molal boiling-point constant for benzene is 2.53°C/m. Its normal boiling point is 80.1°C. 

Kf = molal freezing-point depression constant Kt,= molal boiling-point elevation constant A = absorbance a= molar absorptivity b = path length c= concentration Q = reaction quotient /= current (amperes) q= charge (coulombs) f= time (seconds)... 

Temperature, Heat capacity. Pressure, Dielectric constant. Density, Boiling point. Viscosity, Concentration, Refractive index. Enthalpy, Entropy, Gibbs free energy. Molar enthalpy. Chemical potential. Molality, Volume, Mass, Specific heat. No. of moles. Free energy per mole. 

When 1.645 g of white phosphorus are dissolved in 75.5 g of CS2, the solution boils at 46.709°C, whereas pure CS2 boils at 46.300°C. The molal boiling-point elevation constant for CS2 is 2.34°C/m. Calculate the molar mass of white phosphorus and give the molecular formula. 

Note that the boiling point elevation of a solution is only dependent of molality of solute but not on its chemical composition and it can be used to determine the molality of the solute and its molar mass. A selection of ebullioscopic constants is given in Table 20.9. 

The molal boiling-point elevation constant of benzene is 2.5°C/m. A solution of 15.2 g of unknown solute in 91.1 g benzene boils at a temperature 2.UC higher than the boiling point of pure benzene. Estimate the molar mass of the solute. 

Freezing-point depression and boiling-point elevation (Fig. 14-23) are colligative properties having many familiar practical applications. For reasonably dilute solutions, their values are proportional to the molality of the solution (equations 14.5 and 14.6). The proportionality constants are Kf and K, respectively (Table 14.3). Historically, freezing-point depression was a common method for determining molar masses. 

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