LIQUID SOLUTION

Very Short Answer Type Questions

1.  Define the term Solution?
2.  State the condition resulting in reverse osmosis.
3.  When is the value of Van’t Hoff factor more than one?
4.  What is the sum or the mole fraction of all the components in a three   components system?
5.  Define mole fraction of a component in a solution. How is the molarity of a   solution different from its molarity?
6.  State the formula relating pressure of a gas with its mole fraction in a liquid   solution in contact with it.
7.  What would be the value of Von’t Hoff factor for a dilute solution of K₂SO₄ in   water?
8.  Why is the elevation in boiling point of water different in the following   solutions?                                                                                  (i) 0.1 Molar solution                                           (ii) 0.1 Molar sugar solution.
9.  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?
10.  Define an “ideal solution”.
11.  State Raoult’s law for solutions of non-¬volatile solutes.
12.  Calculate the mass percentage of benzene and carbon tetrachloride if 22g of   benzene is dissolved in 122g of carbon tetrachloride.

Short Answer Type Questions

1.  Sodium chloride aqueous solution freezes at lower temperature than water but   boils at higher temperatures than water. Explain.
2.  Define
    (i) Mole fraction
    (ii) Molarity
3.  Calculate the osmotic pressure in Pascal exerted by a solution prepared by   dissolving l.0 g of polymer of molar mass 185000 in 450 mL of water at 37^oC.
4.  An aqueous solution of glucose is made by dissolving 10 g of glucose (C₆H₁₂O₆)   in 90 g of water at 303 K. If the vapour pressure of pure water at 303 K be 32.8   mm Hg. what would be the vapour pressure of the solution?
5.  Henry Law constant for the solubility of methane in benzene at 298 K is 4.27 ×   105 mm Hg. Calculate the solubility of methane in benzene at 298 K under 760   mm Hg.
6.  When mercuric iodide is added to an aqueous solution of KI the freezing point   is  raised. Why?
7.  State Henry’s law correlating the pressure of a gas and its solubility in a solvent   and mention two applications for the law.
8.  0.01 M solution of KCl and BaCl₂ are prepared separately in water. The freezing   points of KCl is found to be –2°C. What freezing point would you expect for   BaCl₂ solution assuming both KCl and BaCl₂ to be completely ionized.
9.  Calculate the number of moles of methanol in 5 liters of its 2 m solution, if the   density of the solution is 0.981 kg litre^–1. (Molar mass of methanol of 32.0 g   mol^–1).
10.  At a certain temperature, the vapour pressure of CH₃OH and C₂H₅OH solution   is  represented by
     P = 119 x + 135.
     where x is the mole fraction of CH₃OH. What are the vapour pressure of pure   components of this temperature?
11.  Distinguish between the boiling point of a liquid and the normal boiling point of   a liquid.

Very Long Answer Type Questions

1.  The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g of   benzene is lowered by 0.45° C. Calculate.
    (i) The molar mass of acetic acid from this data
    (ii) Van’t Hoff factor [For benzene, K_f = 5.12 K kg mol^–1]
    What conclusion can you draw from the value of Von’t Hoff factor obtained?
2.  One litre aqueous solution of sucrose (molar mass = 342 g mol^–1) weighing   1015 g is found to record an osmotic pressure of 4.82 atm at 293 K. What is the   molarity of the sucrose solution? (R = 0.0821 atm L mol^–1 K^–1)
3.  Calculate the temperature at which a solution containing 54 g of glucose, in   250 g of water will freeze. (K, for water = 1.86 K mol^–1 kg).
4.  What is meant by Van’t Hoff factor?
    The osmotic pressure of a 0.0103 molar solution of an electrolyte is found to be   0.70 aim at 27°C. Calculate the Van’t Hoff factor. (R = 0.082 L atm-mol^–1 K^–1)
    What conclusion do you draw about the molecular state of the solute in the   solution?
5.  Determine the amount of CaCl₂ (i = 2.47) dissolved in 2.5 litre of water such that   its osmotic pressure is 0.75 atm at 27°C.
6.  (A) Among the following compounds, identify which are insoluble, partially   soluble and highly soluble in water.
    (i) phenol (ii) toluene
    (iii) formic acid.
    (B) Based on solute-solvent interactions, arrange the following in order of   increasing solubility in n-octane and explain.
    Cyclohexane, KCl, CH₃OH, CH₃CN
7.  A solution is made by dissolving 30 g of a non-volatile solute in 90 g of water. It   has a vapour pressure of 2.8 kPa at 298 K. At 298 vapour pressure of pure   water  is 3.64 kPa. Calculate the molar mass of the solute.
8.  The boiling point elevation of 0.30 g acetic acid in 100 g benzene is 0.0633 K.   Calculate the molar mass of acetic acid from this data. What conclusion can you   draw about the molecular state of the solute in the solution? [Given Kb for   Benzene = 2.53 K kg mol^–1]
9.  Nalorphene (C₁₉H₂₂NO₃), similar to morphine, is used to combat withdrawal   symptoms in narcotic users. Dose of nalorphine generally given is 1.5 mg.   Calculate the mass of 1.5 × 10^–3 m aqueous solution required for the above   dose.

Long Answer Type Questions

1.  Define the terms molarity’ and molality for a solution. How does a rise in room   temperature change the molarity and molality values of the solution ? How   much urea (moral mass = 60 g mol^–1) should be dissolved in 50 g of water so t   that its vapour pressure at room temperature is reduced by 25%. Calculate   molality of the solution obtained.
2.  100 g of liquid A (molar mass 140 g/mol) was dissolved in 1000 g of liquid B   (molar mass 180 g/mol). The vapour pressure of pure liquid B was found to be   500 torr. Calculate the vapour pressure of pure liquid A and its vapour pressure   in the solution if the total vapour pressure of the solution is 475 torr.
3.  Explain with a suitable diagram and appropriate example, why some non-ideal   solution shows negative deviations.