Molal boiling-point

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... 

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... 

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 ... 

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)... 

You ve tried your hand at problems on molality, boiling points, and freezing points. Are you feeling a little hot under the collcir or as cool as a cucumber Here, we present the answers to the practice problems for this chapter. 

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. 

Rearrange the equation for molal boiling-point elevation to solve for m ... 

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. 

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 ... 

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... 

---