Chemistry. TOPIC : Solution and colligative properties

Size: px

Start display at page:

Download "Chemistry. TOPIC : Solution and colligative properties"

Eustacia James
6 years ago
Views:

1 TOPIC : Solution and colligative properties Date : Marks : 20 mks Time : ½ hr. If 5.85 g of NaCl (molecular weight 58.5) is dissolved in water and the solution is made up to 0.5 litre, the molarity of the solution will be (a) (c) Which of the following modes of expressing concentration is independent of temperature (a) Molarity Molality (c) Formality Normality 3. How many grams of dibasic acid (mol. wt. 200) should be present in 00 ml of its aqueous solution to give decinormal strength (a) g 2 g (c) 0 g 20 g 4. A molal solution is one that contains one mole of a solute in (a) 000 gm of the solvent One litre of the solvent (c) One litre of the solution 22.4 litres of the solution 5. The molarity of pure water is (a) (c) How many moles of water are present in 80 g of water (a) mole 8 mole (c) 0 mole 00 mole 7. Which is not a colligative property (a) Refractive index (c) Depression of freezing point Lowering of vapour pressure Elevation of boiling point 8. According to Raoult's law the relative lowering of vapour pressure of a solution of volatile substance is equal to (a) Mole fraction of the solvent Mole fraction of the solute (c) Weight percentage of a solute Weight percentage of a solvent 9. Isotonic solutions have (a) Equal temperature (c) Equal volume Equal osmotic pressure Equal amount of solute 0. Pressure cooker reduces cooking time for food because (a) Heat is more evenly distributedd in the cooking space Boiling point of water involved in cooking is increased (c) The higher pressure inside the cooker crushes the food material Page of 5

2 Cooking involves chemical changes helped by a rise in temperature. When common salt is dissolvedd in water (a) Melting point of the solution increases Boiling point of the solution increases (c) Boiling point of the solution decreases Both melting point and boiling point decreases 2. Which will show maximum depression in freezing point when concentration is 0.M (a) NaCl Urea (c) Glucose K 2SO 4 3. A 0. molal aqueous solution of the solution will be (a) C C 4. In equimolar solution of glucose, NaCl and BaCl 2, the order of osmotic pressure is as follow (a) Glucose > NaCl > BaCl 2 (c) BaCl 2 > NaCl > Glucose 5. Which of the following will have the highest boiling point at atm pressure (a) 0. M NaCl 0.M sucrose (c) 0.M BaCl2 0.M glucose 6. A solution containing 0g per dm 3 of urea (molecular mass=60g mol - ) is isotonic with a 65% solution of a non-volatile solute. The molecular mass of this non volatile solute is (a) 300 g mol g mol - (c) 200 g mol g mol - 7. The degree os dissociation (α) of a weak electrolyte, A xb y is related to van t Hoff factor (i) by the expression (a) 8. Observe the following abbreviations π obs = observed colligative property π cal = theoretical colligative property assuming normal behavior of solute. Van t Haff factor (i) is given by (a) π 9. The van t Hoff factor I for a compound which undergoes dissociation in one solvent and association in other solvent is respectively (a) 0.000m solution 0.00m solution (c) 0.0m solution 0.m solution 20. Van t Hoff factor of aq. K 2SO 4 at (a) 2 (c) 3 a weak acid is 30% ionized. If K f for water is.86 C/m, the freezing point of (c) -0.8 C C NaCl BaCl > Glucose > 2 Glucose > BaCl 2 > NaCl π (c) infinite dilution has value equal to (c) between 2 and 3 (c) π 2. The freelzing point of the solution M is (a) K K (c) K 50.9 K Page 2 of 5

3 22. Water is added to the solution M such that the mole fraction of water in the solution becomes 0.9. The boiling Point of this solution is (a) K K (c) K K 23. The Van t Hoff factor calculated from association data is always...than calculated from dissociation data (a) Less More (c) Same More or less 24. Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to 4 kg of water to prevent it form freezing at -6 C will be : (K f for water =.86K kg mol -, and molar mass of ethylene glycol = 62g mol - ) (a) g g (c) g g o 25. The molar freezing point constant for water is.86 C mole. If gm of canesugar in 000 gm of water, the solution will freeze at (a).86 o C.86 o C (c) 3.92 o C 2.42 o C ( 2H22O) C are dissolved 26. During depression of freezing point in a solution the following are in equilibrium (a) Liquid solvent, solid solvent Liquid solvent, solid solute (c) Liquid solute, solid solute Liquid solute solid solvent 27. Two solutions of KNO 3 and CH 3 COOH are prepared separately. Molarity of both is 0. M and osmotic pressures are P and P 2 respectively. The correct relationship between the osmotic pressures is (a) P 2 > P P = P2 (c) P > P2 P P + P 28. The osmotic pressure of a 5% (wt/vol) solution of cane sugar at 50 o C is (a) 2.45 atm atm (c) 3.4 atm 4 atm 29. Semipermeable membrane is that which permits the passage of (a) Solute molecules only Solvent molecules only (c) Solute and solvent molecules both Neither solute nor solvent molecules 30. Which inorganic precipitate acts as semipermeable membrane or The chemical composition of semipermeable membrane is (a) Calcium sulphate Barium oxalate (c) Nickel phosphate Copper ferrocyanide 2 P2 = P + P 2 3 P a g e

4 ANSWERS. (a) (a) (a) 24. (a) 5. (a) 6. (c) 7. (a) (c) 5. (c) 6. (a) 7. (a) (c) (a) 25. (a) 26. (a) 27. (c) Solutions. (a) 3. (a).!"#$% ' #!(% )* w w N = 0. = E V( l) (a) The number of moles of solute dissolved in 000 gm of the solvent is called molal solution (a) Molarity of pure water = = 55.6 M (c) Moles of water = = 0 mole NaCl Na + Cl = 2 ions + 2 K SO 2K + SO 3 ions = K2SO 4 give maximum ion in solution so it shows maximum depression in freezing point. 3., -. - / α α α i= i.3, , B (c) BaCl 2 Ba + 2Cl = 3 ion + NaCl Na + Cl = 2 ion Glucose No ionisation BaCl 2 > NaCl > Glucose 5. (c) BaCl 2 gives maximum ion. Hence, its shows highest boiling point. 6. (a) Suppose, the molecular mass of non-volatile solute is M Molar conc. of urea solution > per dm3 A> Molar con. of non-volatile solute solution ) :;< 00/=. 9 )> 9 :;<?/@ for isotonic solution at the same temperature molar concentration are equal > )> A> 9 ).*) *.)>.) 0.2 w = gm Page 4 of 5

5 or M =300g mol - 7. (a) C D EC - α xα yα i = - α + xα + yα i = + α(x+y-) α 2. Solution is H 2O and solvent is C 2H 5OH let 0.9 moles of ethanol 0. mole of H 2O 4.4 gm.8 gm, -. -, - 2 F.*>>> H *G.G, - 4.8, Solute ethanol Solvent H 2O gm 6.2gm, 0.52 F G.A>>> H GAA.L, 3.20, (a) M -NOP,, - 6 B, 6.86 ALG R S o 25. (a) T =.86 =. 86 ; f 27. (c) KNO 3 dissociates completely while CH 3 COOH dissociates to a small extent. Hence, P > P C = π = = 50 mol/l = 5.07 atm o Tf =. 86 C. 30. Copper ferrocyanide ppt. acts as a semipermeable membrane. 5 P a g e

Chapter Solutions. MockTime.com. (a) M urea (b) 0.01 M KNO3 (c) 0.01 M Na2 SO4 (d) M glucose Ans: (c)

Chapter Solutions. MockTime.com. (a) M urea (b) 0.01 M KNO3 (c) 0.01 M Na2 SO4 (d) M glucose Ans: (c) 47 Chapter Solutions 1. Freezing point of an aqueous solution is ( 0.186) C. Elevation of boiling point of the same solution is K b = 0.512 C,Kf = 1.86 C, find the increase in boiling point. [2002] (a)