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Chemistry-Mojo, Practice Questions, , Simplifying Chemistry, , SOLUTION, 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12., 13., 14., 15., , 16., 17., 18., 19., 20., 21., 22., 23., 24., 25., , 26., 27., 28., , 29., 30., 31., 32., 33., , Define osmotic pressure., State the condition resulting in reverse osmosis., State Raoult’s law for a binary solution containing volatile components., Two liquids A and B boil at 145º and 190º C respectively. Which of them has a higher, vapour pressure at 80ºC?, Define `mole fraction’ of a substance in a solution., What is expected value of van’t Hoff factor for K 3[Fe(CN)6] in dilute solution?, Of 0.1 molal solutions of glucose and sodium chloride respectively, which one will have, a higher boiling point?, A and B liquids on mixing produced a warm solution. Which type of deviation is there, and why?, Give reason when 30 ml of ethyl alcohol and 30 ml of water are mixed, the volume of, resulting solution is more than 60 ml., State the formula relating pressure of a gas with its mole fraction in a liquid solution in, contact with it., What would be the value of van’t Hoff factor for a dilute solution of K 2SO4 in water?, In the determination of molar mass of A+B- using a colligative property, what may be, the value of van’t Hoff factor if the solute is 50% dissociated?, How is the molality of a solution different from its molarity?, Two liquids X and Y boil at 110º C and 130º C respectively. Which of them has higher, vapour pressure at 50º C?, Why is the elevation in b.p. of water different in the following solutions?, i. 0.1 molar NaCl solution., ii. 0.1 molar sugar solution., 10 ml of liquid A was mixed with 10 ml of liquid B. The volume of the resulting, solution was found to be 19.9 ml. What do you conclude?, Define Henry’s law about solubility of a gas in a liquid., What are azeotropes? Give an example., Mention a large scale use of the phenomenon called `reverse osmosis’., What is the sum of the mole fractions of all the components in a three component, system?, State Raoult’s law for a solution of volatile liquids., What happens when blood celis are piaced in pure water?, Which will have higher boiling point, 0.1 M NaCl or 0.1 M BaCl2 Solution in water?, On mixing equal volumes of water and ethanol, what type of deviation would you, expect from Raoult’s law?, How is it that the boiling points of the following solutions in water are different :, (a), 0.1 M NaCl solution?, (b), 0.1 M sugar solution?, Give an example of a solution containing a solid solute in a solid solvent., Why is the cooking temperature in pressure cooker higher than in open pan?, Solution A is obtained by dissolving 1g of urea in 100 g of water and solution B is, obtained by dissolving lg of glucose in 100 g of water. Which solution will have a, higher boiling point and why?, Why does molality of a solution remain unchanged with change in temperature while its, molarity changes?, When is the value of van’t Hoff factor more than one?, What do you understand by `colligative properties’?, Define an ideal solution., State any two characteristics of ideal solution., , Tel + 84330 83279, 98376 03674, , Page 1
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Chemistry-Mojo, Practice Questions, , 34., 35., 36., 37., 38., 39., 40., 41., 42., 43., 44., 45., 46., 47., 48., 49., 50., 51., 52., 53., 54., 55., 56., 57., 58., 59., 60., 61., 62., 63., 64., 65., 66., 67., 68., 69., 70., 71., 72., 73., 74., , 76., , Simplifying Chemistry, , Give an example of a compound in which hydrogen bonding results in the formation of, a dimer., Why is an increase in temperature observed on mixing chloroform with acetone?, How is that alcohol and water are miscible in all proportions?, What temperature change is expected during the mixing of two liquids whose solution, shows a negative deviation from Raoult’s law?, Why is benzene insoluble in water but soluble in toluene?, Why is vapour pressure of solution of glucose in water lower than that of water?, How is osmotic pressure dependent upon number of moles of solute?, Distinguish between molarity and molality., Why is osmotic pressur considered as a coiligative property?, Why is ether not miscible in water?, If ΔTb is the elevation in boiling point of a solvent and `m’ is the number of moles of, solute per kg of solvent, what is the relationship between ΔT b and m?, What possible value of ‘I’ will it have if solute molecules undergo association in, solution?, What is the molarity of acetic acid containing 6 g of acetic acid per litre of solution?, What is the molality of ammonia in a solution containing 0.85 g of. NH3 in 100 ml of a, hquid of density 0.85 g cm-3?, Define the term `osmotic pressure’., What is expected van’t Hoff factor for K4 [Fe(CN)6]?, Name two factors on which the vapour pressure of the liquid depends., Define boiling point of a liquid., What change is observed in boiling point of a liquid at higher altitude?, What are isotonic solutions?, What are iso-osmotic solutions?, Give an example of nearly ideal solution., What is a non-ideal solution?, What are the values of ΔH and ΔV for positive deviation from ideality? Give one, example., What are the values of Ptotal, ΔH, ΔV for negative deviation from ideality? Give one, example., What are maximum boiling azeotropes? Give one example., What are minimum boiling azeotropes? Give one example., What factors are responsible for deviations from Raoult’s Law?, Why is boiling point elevated when a nonvolatile solute is added?, Why is freezing point depressed when a non volatile solute is added?, Define molal elevation constant or ebullioscopic constant., Define molal depression constant or cryoscopic constant., Out of 1 M solution of sugar and 1 M solution of urea, which will have greater boiling, point?, What are hypertonic and hypotonic solutions?, When outer shell of two eggs are removed, one of the eggs is placed in pure water and, other is placed in saturated solution of NaCl, what will be observed and why?, Define osmosis., State how does osmotic pressure vary with temperature., If the membrane used in determination of osmotic pressure is slightly leaky, how will it, influence the measured value of osmotic pressure?, Why is osmotic pressure of 1 M KCl is higher than that of 1 M urea solution?, Why is osmotic pressure of 1 M KCl is higher than that of 1 M urea solution?, Which has the highest freezing point :, (a) 1 M glucose, (b) 1 M NaCl, (c) 1 M CaCl2, (d) 1 M AIF3?, What is the value of ‘i’ for Na2SO4. 10 H2O assuming complete ionization?, , Tel + 84330 83279, 98376 03674, , Page 2
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Chemistry-Mojo, Practice Questions, , 77., 78., 79., , 80., 81., , 82., 83., 84., 85., 86., 87., , Simplifying Chemistry, , A 10% colution of urea is isotonic with 20% solution of ‘x’ at same temperature., Calculate molecular weight of x., Calculate molality of 1 M NaNO3 solution. Density of solution is 1.25 g ml-1 and Mol., Wt. of NaNO3 = 85 g mol-1., Red blood cells placed in solution having less than 0.91% NaCl will……….and may, sometimes…………..because NaCl solution will have…………..osmotic pressure than, that of the fluid inside the red blood cell., For which of the following van’t Hoff factor can not be greater than unity :, The elevation in boiling point of 0.1 molal solution of X in water is 0.1536ºC. What, conclusion do you draw about the molecular state of X?, Kb = 0.512 K kg mol-1., What is reverse osmosis? Give its use., Can we separate and azeotropic mixture by distillation? Why do we call it a mixture?, Define molality in terms of elevation in boiling point., 15% by mass of a solution means 15 g of the substance in………………..g of solvent., How does the concept of lattice energy and hydration energy of ions explain the fact that, NaCl is soluble in water but not in benzene?, A person suffering from high blood pressure should take less common salt, why?, , Numericals, 1., 2., 3., , 4., , 5., 6., 7., , 8., , 9., , 10., 11., 12., , 13., , An aqueous solution of sodium chloride freezes below 273 K, Explain the lowering, in freezing point of water with the help of a suitable diagram., Calculate the volume of 80% (by mass) of H 2SO4 (density = 1.80 g/ml) required to, prepare 1 litre of 0.2 molar H2SO4. (Relative atomic masses : H = 1, O = 16.S = 32), Calculate the osmotic pressure of a solution obtained by mixing 100 cm3 of 0.25 M, solution of urea and 100 cm3 of 0.1 M solution of cane sugar at 293 K. [R = 0.082 L, atm mol-1 K-1], 1.0 g of a non-volatile solute was dissolved in 100 g of acetone (mol. mass = 58 g, mol-1) at 198 K. The vapour pressure of solution was found to be 192.5 mm Hg., Calculate the molar mass of solute. [The vapour pressure of pure acetone at 298 K is, 195 mn Hg], Draw a suitable diagram to express the relationship for ideal solutions of A and B, between vapour pressure and mole fractions of components at constant temperature., Claculate the number of moles of methanol in 5 litres in its 2 m solution. If the, density of the solution is 0.981 kg L-1. (Molar mass of methanol = 32 g mol-1), How is relative lowering of vapour pressure defined for a solution consisting of, volatile solvent and non-volatile solute? How is this function related to the mole, fraction of the solvent and of the solute?, In a solution of urea, 3.0 g of it is dissolved in 100 ml of water. What will be the, freezing point of this solution? State the approximation made if any. [K for water =, 1.86 K kg mol-1, molar mass of urea = 60 g mol-1], A solution of 3.800 g of sulphur in 100 g of CS 2 (boiling point = 46.30ºC) boils at, 46.66ºC. What is the formula of sulphur molecule in this solution? (Atomic mass of, sulphur = 32 g mol-1 and Kb for CS2 = 2.40 K kg mol-1), ‘The solution of a non-volatile solute boils at a higher temperature than the pure, solvent.’ Show this relationship on a graphic diagram., With the help of a neat diagram indicate why the solution of a non-volatile solute, should freeze at a temperature lower than the freezing point of the pure solvent., For determining molar masses ofr macromolecular substances in solution, the, osmotic pressure measurement method is preferred over measurement method of any, other colligative property of solution. Give two reasons for it., Give one example each of miscible liquid pairs showing positive and negative, deviations from Raoult’s law. Give one reason each for such deviations., , Tel + 84330 83279, 98376 03674, , Page 3
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Chemistry-Mojo, Practice Questions, , Simplifying Chemistry, , 14. An aqueous solution of glucose is made by dissolving 10 g of glucose (C6H12O6) in, 90 g of water at 303 K. If vapour pressure of pure water at 303 K be 32.8 mm Hg,, what would be the vapour pressure of the solution?, 15. What is osmotic pressure and how is it related with the molecular mass of nonvolatile solute?, 16. Calculate molarity and molality of a 13% solution (by weight) of sulphuric acid. Its, density is 1.020 g cm-3 (Atomic mass H = 1, O = 16, S = 32 u), 17. Explain with a suitable diagram and appropriate example why some non-ideal, solutions show positive deviation from ideal behaviour., 18. What is meant by abnormal molecular mass of solute? Discuss the factors which, bring abnormality in the experimentally determined molecular masses of solutes, using colligative properties., 19. Vapour pressure of pure water at 35º C is 31.82 mm Hg. When 27.0 g of solute is, dissolved in 100 g of water (at the same temperature) vapour pressure of the solution, thus formed is 30.95 mm Hg. Calculate the molecular mass of the solute., 20. The vapour pressure of pure liquids A and B are 70 mm Hg and 99 mm respectively, at 25ºC. The mole fraction of ‘A’ in a solution of the two is 0.3. Assuming that A and, B form an ideal solution, calculate the partial pressure of each component in, equilibrium with the solution., 21. The freezing point of pure nitrobenzene is 278.8 K. When 2.5 g of nitrobenzene, the, freezing point of solution is found of be 276.8 K. If the freezing point depression, constant of nitrobenzene is 8.0 K kg mol-1, what is the molar mass of unknown, substance?, 22. The solubility of Ba (OH)2. 8H2O in water at 288 K is 5.6 g per 100 g of water. What, is the molality of the hydroxide ions in saturated solution of Ba (OH) 2. 8H2O at 288, K?, 23. Osmotic pressure of a solution containing 7 g of dissolved protein per 100 cm3 of the, solution is 20 mm Hg at 310 K. Calculate the molar mass of protein. [R = 0.082 L, atm K-1 mol-1], 24. Calculate the molality of KCl solution in water, given that the depression in freezing, point is 2 K. [Kf for water = 1.86 K kg mol-1]., IMPORTANT QUESTIONS, 25. What type of non-idealities are exhibited by cyclohexane-ethanol and acetonechloroform mixture? Give reasons for your answer., 26. 10 g of an organic substance is dissolved in two litres of water and gave an osmotic, pressure of 0.60 atm at 27ºC. Calculate the molecular mass of the substance. (R –, 0.082 L atm mol-1 K-1), 27. A solution of sucrose (molecular weight 342) is prepared by dissolving 68.4 g of it, per litre of solution. What is osmotic pressure at 300 K? [R = 8.3 14 k Pa dm 3 K-1, mol-1], 28. A sugar syrup of weight 214.2 g contains 34.2 g of sugar (C 12H22O11). Calculate (i), mole fraction of sugar syrup., 29. Calculate the molality of K2CO3 solution which is formed by dissolving 2.5 g of it in, one litre of solution. Density of solution is 0.85 g ml -1., 30. The freezing point of a solution composed of 5.85 g of NaCl in 100 g water is –, 3.348ºC. Calculate the van’t Hoff factor ‘i’ for this solution, K (water) = 1.86 K kg, mol-1., 31. An electrolyte AB is 50% ionized in squeous solution. Calculate the freezing point of, 1 molal aqueous solution., 32. The boiling point of a solution of urea in water is 100. 13ºC. Calculate the freezing, point of solution. (Kf and Kb for water are 1.86 K/m and 0.52 K/m respectively)., , Tel + 84330 83279, 98376 03674, , Page 4
