Colligative Property and Solution Objective

PHYSICAL CHEMISTRY

By: Shailendra Kumar

PHYSICAL CHEMISTRY by:

SHAILENDRA KR.

Meq. Approach

Classes at: SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna

Topic: Colligative Property 1. Which of the following set(S) of chemical compounds is/are used as semi-permeable membrane ? (A) Calcium phosphate, Cellulose nitrate

(B) Calcium phosphate, Copper ferrocyanide

(C) Cellulose nitrate, Copper ferrocyanide

(D) Copper ferrocynide, Copper sulphate

2. A 0.2 molal aqueous solution of an acid (AH) of degree of dissociation 20%, having freezing point (Given Kf for water is 1.86°C kg mole–1). (A) –0.45°C

(B) –0.50°C

(C) –0.31°C

(D) –0.53°C

3. 10 ml 1.0 N HCl neutralises a sample of water of 100 ml. The hardness of water in the term of mg equivalent/litre of calcium carbonate will be (A) 4.5 mg equivalent/litre

(B) 9.8 mg equivalent/litre

(C) 2.4 mg equivalent/litre

(D) 200 mg equivalent/litre

4. For a binary solution, showing a negative deviation from Raoult’s law correct statement(s) is/are (A) ∆Hmixing < 0 o A

(C) PA < P XA

(B) ∆Vmixing < 0 (D) ∆Smixing < 0

5. When 0.1 M solution of glucose and 0.1 M solution of sucrose atre placed on two sides of the semipermeable membrane to equal heights. Then, (A) there will be no net movement across the membrane because they are isotonic. (B) glucose solution will flow towards sucrose solution because glucose solution is hypotonic. (C) sucrose solution will flow towards glose solution because glucose solution is hypertonic. (D) water will flow from sucrose solution to glucose solution because sucrose solution is hypotonic. 6. The latent of vaporisation of water is 9.7 kJ/mole and if the boiling point is 373 K, the ebullioscopic constant of water will be (A) 0.513 K kg mole–1

(B) 1.026 K kg mole–1

(C) 1.26 K kg mole–1

(D) 1.832 K kg mole–1

7. The relationship between osmotic pressure (P1, P2 and P3) at a definite temoerature when 1 g glocose, 1 g urea and 1 g sucrose are dissolved in 500 ml of water is

1. 2.

(A) P1 > P2 > P3

(B) P3 > P1 > P2

(C) P2 > P1 > P3

(D) P2 > P3 > P1

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PHYSICAL CHEMISTRY

By: Shailendra Kumar

8. An ideal solution has two components A and B. A is more volatile than B, i.e. POA > POB and also POA > Ptoal . If XA and YA are mole-fractions of components A in liquide and vapour Phases, then (A) XA = YA

(B) XA > YA

(C) XA < YA

(D) information in not enough to correlate XA with YA

9. The boiling point of an azeotropic mixture of water-ethanol is less than that of both water and ethanol. Then, (A) the mixture will show negative deviation from Raoult’s law. (B) the mixture will show positive deviation from Raoult’s law. (C) the mixture will show no deviation from Raoult’s law. (D) the zeotropic mixture cannot be considered as true solution. 1/2 (C6H5OH)2. If x is the degree of association 10. Phenol association in benzene as C6H5OH of phenol, then the total number of moles of particles present at equilibrium is (A) 1 – x

(B) 1 + x

(C) 1 + x/2

(D) 1 – x/2

11. When 0.6 g of an organic acid dissolved in 200 ml of water is extracted with 50 ml of ether, it is found on analysis, that 0.4 of the organic acid goes into the ether layer. Which one of the following is the ratio of the solubility of the acid in ether and water? Sether

(A) Swater = 0.125 (B) Sether = 2 Swater

Sether

(B) Swater = 0.5 (C) Sether = 8 S water

12. The vapour pressures of pure A and B are 0.02 and 0.04 bar respectively. Their liuid mixture behaves as an ideal solution. If the mole fraction of B in the liquid phase is 0.50, then its mole fraction in the vapour in equilibrium with the liquid phase is equal to (A) 0.50

(B) 0.33

(b) 0.67

(C) 0.25

13. Which of the solutions will have the maxinun boiling point? (A) 0.1 M NaCl

(B) 0.1M BaCl2

(C) 0.1 M Na2SO4

(D) 0.1 N K2SO4

14. The freezing point of the four solutions given below will be of the order I:

0.1 M Glucose

II: 0.1 M Na3PO4

III: 0.1 M NaCl

IV: 0.1 M K4 [Fe(CN)6)]

(A) I < II < III < IV

(B) IV < II < III < I

(C) I < III < II < IV

(D) IV < I < III < II

15. Two components A and B form abn ideal solution. The mole-fraction of A and B in ideal solution are XA and XB, while that of in vapour phase, these components have their mole fraction YA and YB. Then the sop of plot of 1/XA Vs 1/YA will be O

(A)

PA

O

PB

(C) P B°

1. 2.

O

(B)

PB

O

PA

(D) PºA–P°B

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PHYSICAL CHEMISTRY

By: Shailendra Kumar

16. In the above QUESTION, the plot of 1/XA Vs 1/YA will be O

(A)

O

O

PB -PA

(B)

O

PB O

(C)

O

PA -PB O

PA O

PA -1

(D)

O

PB

PA -1 O

PB

17. the Van’t Hoff’s (i) for a 0.1 M Ba(NO3)2 solution is 2.74. The degree of its dissociation at the same temperature will be (A) 83%

(B) 87%

(C) 100%

(D) 78%

18. Which of the following satatement(s) is/are correct about azeotropic mixture? (A) it is a constant boiling mixture. (B) components of azeotropic mixture cannot be separated by fractional distillation. (C) an azeotropic mixture of water-alcohal contains only 4.4% of water. (D) a liquid pair which shows a positive deviation from Raoult’s law may behave as a minimum boiling point azeotrope. 19. When a molecule of a solute dissociates in a solvent to give n ions. The degree of dissociation is given by 1-i

(A) α = 1- 1

n

(C) α =

i-1 1-n

(B) α =

1-i n-1 Ê ö

! (D) α = Á ! Á ! è ø

20. The azeotropic mixture of water (B. P. 100°C) and HCl (B. P. = 85°C) boils at about 110°C. During distillation of this mixture it is possible to obtain (A) pure HCl

(B) pure H2O

(C) pure H2O as well as pure HCl

(D) neither H2O nor HCl

21. When 100 ml of a liquide A is mixed with 25 ml of a liquid, B, a non-ideal solution A-B is produced. The volume of the resultion solution will be (A) 75 ml

(B) 125 ml

(C) 75 ml or 125 ml

(D) less or more than 125 ml

22. For the depression of freezing point experiment. The correct statement(s) is/are (A) the vapour pressure of pure-solvent is more than that of solution. (B) the vapour pressure of pure-solvent is less than that of solution. (C) only solute molecules solidify at the freezing point. (D) only solvent molecules solidify at the freezing point.

1. 2.

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PHYSICAL CHEMISTRY

By: Shailendra Kumar

23. A solution containing 4.0 g of PVC in 1 litre of dioxane (industrial solvent) was found to have an osmotic pressure 6.0 × 10–4 atmosphere at 27°C, the value of R used is 0.082 litre atmosphere deg–1. The molecular mass of the polymer will be (A) 1.6 × 104

(B) 1.6 × 105

(C) 1.6 × 103

(D) 1.6 × 102

24. The vapour pressures of pure benzene and pure toluene at a definite temperature are found to be 120 mm Hg and 100 mm Hg respectively. If equilimolars of benzene and toluene are mixed to prepare an ideal solution. The vapour pressure of the solution at the same temperature will be (A) 120 mm Hg

(B) 100 mm Hg

(C) 220 mm Hg

(D) 110 mm Hg

25. The vapour pressure of a solution of 5 g of non-electrlyte in 100 g of water at a definite temperature is 2985 Nm–2. The vapour pressure of pure water at the same temperature is 3000 Nm–2. The molecular mass of the solute dissolved in water is (A) 180

(B) 360

(C) 300

(D) 210

26. When HgI2 is added to an aques solution of KI, then (A) freezing point decreases

(B) freezing point increases

(C) freezing point remains contant

(D) nothing can be predicted

27. which of the following unit(s) used to represent concentration is/are independent of temperature? (A) molarity

(B) molality

(C) mole fraction

(D) normality

28. The decreases in vaoiur of a pure solvent is observed to be 10 mm Hg when a non-volatile solute is added to solvent. The mole fraction of solute in the solution is 0.2. What should be the mole fraction of same solvent if decrease in vapour pressure is to be 20 mm Hg ? (A) 0.1

(B) 0.6

(C) 0.3

(D) 0.2

29. A binary solution contains x1 and x2 mole fractions of two components having vapour pressure po1 and po2 in their pure states. The total pressure of the above the solution is (A) ( po1 – po2 )x1 + po2

(B) ( po2 – po1 )x1 + po2

(C) ( po1 – po2 )x1 + po1

(D) ( po2 – po1 )x1 + po1

30. The boiling point elevation constant for toluene is 3.32 K kg mol–1. The normal boiling point of toluene is 110.7°C. The enthalpy of vaporisation of toluene would be nearly (A) 17.0 kJ mol–1

(B) 34.0 kJ mol–1

(C) 51.0 kJ mol–1

(D) 68.0 kJ mol–1

31. The normal boiling point of water is 373 K. Vapour pressure of water at 25°C is 23 mm Hg. If enthalpy of vaporisation is 40.656 kJ mol–1, the boiling point of water at 23 mm Hg pressure would be

1. 2.

(A) 250 K

(B) 294 K

(C) 230 K

(D) 290 K

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PHYSICAL CHEMISTRY

By: Shailendra Kumar

32. The vapour pressure of an aqueous solution of sucrose at 373 K is found to be 750 mm Hg. The molality of the solution at the same temperature will be (A) 0.2

(B) 0.71

(C) 0.74

(D) 1.3

33. If Mnormal is the normal molacular mass and α is the degree of dissociation of K3[Fe(CN)6], then the abnormal molecular mass of the complex in the solution will be (A) Mnormal (1 + 2α α)–1 (C) Mnormal (1 + α)–1

(B) Mnormal (1 + 3α α)–1 (D) equal to Mnormal

34. Dry air was passed successively through a solution of 5 g of a solute in 80 g of water and then through pure water. The loss in weight of solution was 2.50 g and that of pure solvent 0.04 g. The molecular weight of the solute would be (A) 70.31

(B) 7.143

(C) 703.1

(D) 7031

35. For exact determination of molecular mass (A) solute must be volatile

(B) solution must be very dilute

(C) solution must be of similar components (D) solute must be dissociation or associated 36. On February 14,2003, the temperature in Manali was found to be –10°C. A car was used, whose radiator was filled with 5 L of water. What quantity of antifreezing agent ethylene glycol were assed to water of radiator in order to use the car for tracelling? (given Kf of water = 1.86 K kg mole–1, d ≈ 1 g ml–1) (A) 3200 g

(B) 1670 g

(C) 3000 g

(D) 2100 g

37. The distribution constant (CA/CB) of a solute in two immiscible liquids A anB is 100. If one litre of 0.001 M solution of the solute in B is shaken with 100 ml of the liquid A, than after equilibrium, CB will be (A) 0.0009 M

(B) 0.0001 M

(C) 0.0005 M

(D) 0.0002 M

38. Two molecules of acetic-acid in benzene associate to form a dimer. If α is the degree of association, it will be related with Van’t Hoff’s factor i as (A) α =

i-1

(B) α = 2(1 - i)

2

(C) α = 3(i - 1)

(D) α =

2i - 1 2

39. ∆Tf repersents the depression in freezing point of the solvent in a solution of a non-volatile solute of ∆Tf / m) equal to molality m, the quantity lim (∆ m→ →0

1. 2.

(A) ZERO

(B) infinite

(C) two

(D) one

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PHYSICAL CHEMISTRY

By: Shailendra Kumar

40. Which of the colligative properties is most suitable to determine molecular mass of proteins ? (A) elevation in boiling point

(B) depression in freezing point

(C) osmotic pressure

(D) relative lowering of vapour pressure

41. Consider 0.1 M solution of two solutions of two solutes X and Y. The solute X behaves as a univalent electrolyte while the solute Y dimerises in solution. Which of the following statements are correct regarding these solutions? 1. The boiling point of the solution of X will be higher than that of Y. 2. The osmatic pressure of the solution of Y will be lower than that of X. 3. The freezing point of the solution of X will be lower than that of Y. 4. The relative lowering of vapour pressure of both the solutions will be the same. select the correct answer from the options given below (A) 1, 2 and 3

(B) 2, 3 and 4

(C) 1, 2 and 4

(D) 1, 3 and 4

42. The total vapour pressure of a binary solution is given by; P = (110XA + 125XB) mm Hg where, XA and XB are the mole fractions of components A and B. This indicates that (A) the vapour pressure of solution (nA = nB) is less than the pure B component. (B) the vapour pressure of solution (nA = nB) is more than that pure A component. (C) vapour pressure of pure A component is 110 mm Hg and that of pure B is 125 mm Hg. (D) the vapour pressure of pure A and B are 125 mm Hg and 110 mm Hg respectively. 43. The vapour pressure of two solutions of solute A and B are 160 mm Hg and 200 mm Hg respectively. If 2 moles of each A and B are present in a solution A-B. Then, solution A-B (A) shows ideal behavior, if the vapour pressure of solution is 300 mm Hg. (B) shows positive deviation from Raoult’s law, if the vapour pressure of the solution is 300 mm Hg. (C) shows negative deviation from Raoult’s law, if the vapour pressure of the solution is 300 mm Hg. (D) both A and C are correct. 44. The cryoscopic constant of water is 1.86 K kg mole–1. A 0.01 molal acetic acid solution produces a depression of 0.0193°C in the freezing point. The degree of dissociation of acetic acid is (A) ZERO

(B) 4%

(C) 8%

(D) 40%

45. Consider the following statements: 1. osmatic pressure method is the most useful method for determining the molecular weight of macro-molecules. 2. the molecular weight of the macro-molecules does not change in presence of an electrolyte in the solution. 3. collogative properties are helpful to determine average molecular weight of macro-molecules. Which of the above statement(s) is/are correct?

1. 2.

(A) 1 alone

(B) 1 and 3

(C) 2 and 3

(D) 2 alone

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