Boiling point elevation molal constant

IQ = molal freezing-point depression constant Kb = molal boiling-point elevation constant Kf for water = 1.86 K kg mol-1 for water = 0.512 K kg mol-1 AT = iKf x molality ATb = iKb x molality n = MRT... 

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)... 

Molal Boiling-Point-Elevation Constants (Afb) and Molal Freezing-Point-Depression Constants (ACf) for Some Common Substances... 

What is the molality of an aqueous glucose solution if the boiling point of the solution at 1 atm pressure is 101.27°C The molal boiling-point-elevation constant for water is given in Table 11.4. 

A solution prepared by dissolving 5.00 g of aspirin, C9H8O4, in 215 g of chloroform has a normal boiling point that is elevated by AT = 0.47°C over that of pure chloroform. What is the value of the molal boiling-point-elevation constant for chloroform ... 

A solution of citric acid, C HsC, in 50.0 g of acetic acid has a boiling point elevation of AT = 1.76°C. What is the molality of the solution if the molal boiling-point-elevation constant for acetic acid is Kb = 3.07 (°Okg)/mol. 

Molal boiling-point elevation constant a constant characteristic of a particular solvent that gives the change in boiling point as a function of solution molality used in molecular weight determinations. (17.5)... 

The molal boiling point elevation constant, S), is the difference in boiling points between aim nonvolatile, nonelectrolyte solution and a pure solvent. It is expressed in units of °C/w and varies for different solvents. Values of A j, for several common solvents are found in Table 15-4. Note that water s A j, value is 0.512°C/w. This means that a m aqueous solution containing a nonvolatile, nonelectrolyte solute boils at 100.512°C, a temperature 0.512°C higher than pure water s boiling point of 100.0°C. 

The term A7)j represents the elevation of the boiling point of the solvent, that is, the boiling point of the solution minus the boiling point of the pure solvent. The m is the molality of the solute, and is a proportionality constant called the molal boiling point elevation constant. This constant is different for different solvents and does not depend on the solute (Table 14-2). 

K = molal freezing-point depression constant = molal boiling-point elevation constant... 

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. 

The molal boiling point elevation constant, Kb> thus can be calculated from the properties of the solvent, namely 7J, Mi, and AHyap. Table 5.3 gives Kt values calculated in this way, as well as experimental Kt, values obtained by direct rneasurement of ATb for solutions of known molality. The agreement is quite satisfactory. 

Table 5.3 Molal Boiling-Point Elevation Constants...

The temperature difference is equal to the molal boiling point elevation constant multiplied by the solution s molality. 

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