Water cryoscopic constant

One-fifth mole of a weak monobasic acid is dissolved in 1000 cc of water (cryoscopic constant 1.86 degrees). The freezing point of the resulting solution is —0.396 degrees. Calculate for the acid. 

SAQ 5.6 Pure water has a normal freezing point of 273.15 K. What will be the new normal freezing point of water if 11 g of KCI is dissolved in 0.9 dm3 of water The cryoscopic constant of water is 1.86 Kkg-1 mol-1 assume the density of water is 1 gem-3, i.e. molality and molarity are the same. 

You dissolve 90 g of sucrose (molar mass = 342 g/mol) in 1000 g of water. What is the molality of the solution If the cryoscopic constant for water is 1.9 degrees/molal, what is the freezing point of the solution ... 

The cryoscopic method was used in Hantzsch s original work 53, 54) and was later developed by Hammett and Deyrup 56) and by Gillespie et al. 48). Sulfuric acid freezes at 10.371 C and has a relatively large molal freezing-point depression or cryoscopic constant fc = 6.12 32). It is thus a convenient solvent for cryoscopic measurements provided that adequate precautions are taken to prevent absorption of water from the atmosphere. From freezing-point measurements the number, v, of moles of particles (ions and molecules) produced by one mole of any solute may be obtained. Some examples are given in Table IV. 

Deliquescent, orthorhombic, elongated, six-sided tablets from dimethyl phthalate. dj 1.282. mp 45-46. bp0J 83. Fomin of dicyandiamide begins at 122. Dipole moment in benzene at 2Cryoscopic constant (water) 26.8-28.4. Sp ht 0.547 cal/g/ C between 0° and 39. Heat of formation 14.05 kcal/mole (25 ) heat of combustion —176-4 kcal/-mole (25 ) heat of fusion 2.1 kcal/mole. Heat of vaporization 16.4 kcal/mole. Soly (g/100 g soln) in water at 15 77.5, at 43 100 in butanol at 20 28.8, in methyl ethyl ketone 50.5, in ethyl acetate 42.4. Sol in alcohols, phenols, amines, ethers, ketones. Very sparingly sol in benzene, haJogeaated hydrocarbons. Practically insol in cyclohexane. Solid cyanamide should be stored in a cool, dry place. Polymerizes at 122. Optimum pH for storage of solns is 4, Attacks various metals. Solns can be stored in grass provided they are stabilized with phosphoric, acetic, sulfuric, or boric acid. LDM in rats 125 mg /kg orally. 

Peterson and Rodebush""" made precise measurements by the differential equilibrium method on a number of non-electrolytes (toluene, methanol, ethanol, water, acetic acid and benzoic acid). Precise measurements by a similar technique on carboxylic acids"" and tetraalkyl-ammonium salts"" "" were made by Kraus and co-workers. The cryoscopic constant is = 5.089 K kg mol"Measurements on the tetraalkylammonium salts were made over a wide concentration range and degrees of association as a function of concentration were evaluated. The association of phenolic compounds in benzene has been studied... 

This means that the melting point decreases by almost 10 K due to the elevated pressure therefore, the temperature of i = —2 C at the bottom of the Mariana Trench is possible. Due to the salts dissolved in the sea water, the melting point is further lowered (cryoscopic constant. Section 8.1.1.1), but the main effect is caused by the pressure elevation in this case. 

Calculate the cryoscopic constant of water and naphthalene using the following pure component data. 

In an aqueous sugar solution, the freezing point of water at atmospheric pressure is lowered by 0.1 K. Estimate the osmotic pressure of the solution at 20 °C. Use the cryoscopic constant of water given in Example 8.7. 

On freezing, water forms pure ice and PEG molecnles concentrate in the nnfrozen phase, whose volume enhances with CpEo and the freezing temperatnre of water lowers. This temperature depends on the molecular weight of polymers and the cryoscopic constant of water. The concentration of PEG in the unfrozen phase can be estimated from the relationship between the H NMR signal intensity of water and PEG, as at CpEo=50 wt%, they have the signals with equal intensity and 8h,iso 5.0 ppm (OH) and 4.2 ppm (CHj) (Figure 5.57a). The last solution is frozen as eutectic mixture. 

Three hundred precipitations of the aqueous solution with alcohol were necessary before a constant-rotating product was obtained. [a]D20 = — 51.4° (water). (Alcohol was removed from the sample by repeated evaporation with water followed by drying for two hours at 80° in a high vacuum.) Cryoscopic determination of the molecular weight in water solution gave an average of 2600 for the original and 2825 for the deacetylated product. 

The oligomer obtained from an initial isobutene pressure of 100 to 300 mm had a cryoscopically determined DP of 5, and approximately 2000 such pentamer molecules were formed per molecule of water added. When the initial pressure of isobutene was 1500 mm, the DP of the oligomer was 30. These observations show the dominance of transfer processes. It was also concluded that, since the first order rate constant for the... 

Plot the change in the saturated vapour pressure of water over pure water and an aqueous solution of sugar (sodium chloride) against the temperature. How does the freezing (boiling) point of water change when it contains solutes (sugar, sodium chloride) Define the cryoscopic and ebullioscopic constants of water. What is their numerical value State Raoult s laws and write their mathematical expression. How can the molecular masses of solids be determined ... 

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