Van’t Hoff Factor

In 1886, Van’t Hoff introduced a factor 'i' called Van’t Hoff factor to express the extent of association

or dissociation of solute in solution.

Related Questions;

(1) calculate weight of urea which must be dissolved in 400 gm of water so that final has V.P. 2% than V.P. of pure water?

(2) 10 gm of a solute is dissolved in 80 gm of acetone V.P. of solution is 271 mm Hg. If V.P. of pure acetone is 283 mm of Hg. calculate molar mass of solute.

(3) Vapour pressure of a solution containing 6 gm of non volatile solute in 180 gm of water is 20 torr/mmHg. If 1 mole of water is further added in to the V.P. increases by 0.02 torr. calculate the V.P. of pure water and molecular wt of the non volatile solute.

(4) An aqueous solution has 5% urea and 10% glucose by weight. what will be the freezing point of this solution ? ( Kf = 1.86 K Kg per mole)

(5) Acetic acid dimerised to an extent of 30% in benzene . The observed molecular mass (in gm) is...

(6) How much ice will separate if a solution containing 25 g of ethylene glycol [C2H4(OH) 2] in 100g of water is cooled to 10°C? Kf(H2O) = 1.86 (25.05 g)

(7) The dielectric con stant of H2O is 80. The electrostatic force of attraction between Na+ and Cl–will be.

(8) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.

(9) An aqueous solution has 5% urea and 10% glucose by weight. what will be the freezing point of this solution ? ( Kf = 1.86 K Kg per mole)

(10) Acetic acid dimerised to an extent of 30% in benzene . The observed molecular mass (in gm) is...

(11) How much ice will separate if a solution containing 25 g of ethylene glycol [C2H4(OH) 2] in 100g of water is cooled to 10°C? Kf(H2O) = 1.86 (25.05 g)

(12) The dielectric con stant of H2O is 80. The electrostatic force of attraction between Na+ and Cl–will be.

(13) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.

(14) How can derivatives relation between relative lovering of vapour pressure and molality?

(15) A saturared solution of XCl3 has a vapour pressure 17.20 mm Hg at 20°C, while pure water vapour pressure is 17.25 mm Hg. Solubility product (Ksp) of XCl3 at 20°C is

(16) Calculate the percentage degree of dissociation of an electrolyte XY2 ( normal molar mass=165) in water if the observed molar mass by measuring elevation in boiling point is 65.5.

(17) Which of the following pair of solution (aq.) contain isotonic solution at same temperature? (Assume 100 % ionisation of electrolytes) 

(1) 0.1 M NaCI and 0.2 M CaCI2

(2) 0.1 M NaCI and 0.3 M AICI3 

(3) 0.3 M NaCI and 0.1 M AICI3 

(4) 0.3 M NaCI and 0.2 CaCI2

(18) Freezing point of pure liquid A is T K. If some amount of non-electrolyte non-volatile impurity is added in A, an ideal solution is formed. On cooling at 200 K, only 30% (by mass) liquid A is present and at 201 K, 60 % (by mass) liquid A is present. The value of T is .

(19) Liquid A and B form ideal solution at temperature T. Mole fraction of A in liquid and vapour phase are 0.4 and 4/13 respectively, when total pressure is 130 torr. The vapour pressure (in torr) of A and B in pure state at temperature T are respectively.

(20) 2 millimolar solution of sodium ferrocyanide is 60% dissociated at 27°C. osmotic pressure of the slotution is .

(21) Decimolar solution of K4[Fe(CN)6] dissociate by 60% at 27°C. Determine osmotlc pressure in Nature/M2.

(22) A complex is represented as CoCl3.xNH3.Freezing point of its 0.1 molar solution is - 0.558° C (Kf = 18.6) Assuming 100 % dissociation and coordination number of Co(iii) is six , the what is the complex formula ?

(23) A complex is wrltten as M(en)y.xBr. lts 0.05 molar solution shows 2.46 atm osmotlc pressure at 27°C. Assuming 100 % ionisaton and coordination number of metal (iii) is six, complex may be:

(24) Find the freezing point of a solution when 5 moI of Kl is mixed with 1 moI of HgCI2 in 3500 g of H20. Kf of H20 1.86 K/m. (KI + HgCI2 --> K2Hgl4 + KCI)

(25) A mixture of weighing 228 g contain CaCl2 and NaCl . If this mixture is dissolved in 10 kg of water and form ideal solution that boil at 100.364 ℃ The mol % of NaCl in mixture is [ kb of water = 0.52 K per mol Kg]

(26) What is the Raoult's law and it's application ?

(27) What is Vapour pressure of liquid ?

(28) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.

(29) Aqueous solution of 0.004 M Na2SO4 and 0.01 M glucose are iosotonic .The degree of dissociation of Na2SO4 is ..

(30) A saturared solution of XCl3 has a vapour pressure 17.20 mm Hg at 20°C, while pure water vapour pressure is 17.25 mm Hg. Solubility product (Ksp) of XCl3 at 20°C is.

Colligative Properties

These are the properties that depend on the concentration of solute molecule or ions in solution but not on the chemical identity of the solute. 

For example, addition of ethylene glycol to water lowers the freezing point of water below 0°C. 

The magnitude of freezing point lowering is directly proportional to the number of solute molecules added to a particular quantity of solvent. 

(1) If 0.01 mole of ethylene glycol is added to 1 kg of water, the freezing point is lowered to - 0.019°C while

(2)  On adding 0.020 mole of ethylene glycol to 1 kg of water, the freezing point is lowered to -0.038°C. 

The various colligative properties are 

(1) Relative lowering of vapour pressure 

(2) Osmotic pressure 

(3) Elevation of boiling point 

(4) Depression of freezing point 

Henry's law constant for CO2​ in water is 1.67×10^8 Pa at 298K. Calculate the quantity of CO2​ in 500 ml of soda water when packed under 2.5 atm CO2​ pressure at 298K.