Solutions quiz

Which concentration term is independent of temperature?

The solubility of a gas in a liquid increases with:

A solution of chloroform and acetone shows:

Which of the following is not a colligative property?

The van't Hoff factor for acetic acid that dimerises completely in benzene is:

Which 0.1 m aqueous solution has the lowest freezing point?

For an ideal solution:

The unit of ebullioscopic constant Kb is:

Scuba divers face the bends because of the release of dissolved:

A 0.9% (w/v) NaCl solution is isotonic with blood. A red blood cell placed in 2% NaCl solution will:

Why do gases always tend to be less soluble in liquids as the temperature is raised? (2 marks)

What is meant by positive deviation from Raoult's law? Give one example. (2 marks)

Why is the freezing point depression of 0.1 m NaCl nearly twice that of 0.1 m glucose? (2 marks)

Define the cryoscopic constant. On what factors does it depend? (2 marks)

What is reverse osmosis? Give one practical application. (2 marks)

What are isotonic solutions? Give one example. (2 marks)

Why is the vapour pressure of a solution of glucose in water lower than that of pure water? (2 marks)

What is the significance of Henry's law constant KH? A gas with higher KH is more or less soluble? (2 marks)

Explain why aquatic animals are more comfortable in cold water than in warm water. (2 marks)

Write two differences between ideal and non-ideal solutions. (2 marks)

The vapour pressures of pure liquids A and B are 450 and 700 mm Hg at 350 K. Find the composition of the liquid mixture if the total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase. (3 marks)

The vapour pressure of water is 23.8 mm Hg at 298 K. Calculate the vapour pressure of a solution made by dissolving 50 g of urea (M = 60 g mol^-1) in 850 g of water. (3 marks)

Calculate the freezing point of a solution containing 0.1 mol of NaCl in 500 g of water, assuming complete dissociation (Kf = 1.86 K kg mol^-1, freezing point of water = 273.15 K). (3 marks)

Calculate the osmotic pressure of a 0.1 M glucose solution at 27 degree C (R = 0.083 L bar mol^-1 K^-1). What would be the osmotic pressure of 0.1 M NaCl at the same temperature assuming complete dissociation? (3 marks)

5 g of NaOH (M = 40 g mol^-1) is dissolved in water to make 450 mL of solution. Calculate the molarity. If instead 5 g of NaOH is dissolved in 450 g of water, calculate the mass percentage of NaOH. (3 marks)

Read the passage and answer the questions. In cold countries, ethylene glycol is added to the water in car radiators. A mechanic adds 62 g of ethylene glycol (M = 62 g mol^-1) to 1 kg of water (Kf = 1.86 K kg mol^-1). (i) Calculate the depression in freezing point. (ii) Name the colligative property involved. (iii) Why is ethylene glycol preferred over common salt for this purpose? (5 marks)

Read the passage and answer the questions. Desalination plants in Chennai use reverse osmosis to convert sea water into drinking water. Pressure greater than the osmotic pressure of sea water is applied on the sea water side of a membrane made of cellulose acetate. (i) What happens when this pressure is applied? (ii) Why must the pressure exceed the osmotic pressure? (iii) Why is cellulose acetate used as the membrane? (5 marks)

Read the passage and answer the questions. Scuba divers breathe air at high pressure under water. When they come up too quickly, they feel pain in their joints. To avoid this, tanks are filled with air diluted with helium. (i) Which law explains this? (ii) Why do divers suffer from the bends? (iii) Why is helium used to dilute the air? (5 marks)

Read the passage and answer the questions. A student found the molar mass of acetic acid in benzene by freezing point depression to be about 120 g mol^-1, while in water it came out slightly less than 60 g mol^-1. (i) Explain the abnormal value in benzene. (ii) Explain the value in water. (iii) What is the approximate van't Hoff factor in benzene? (5 marks)

Read the passage and answer the questions. When ethanol and water are mixed, the vapour pressure of the solution is higher than that predicted by Raoult's law. A 95.6% ethanol-water mixture boils at a constant temperature of 351.3 K and cannot be further concentrated by fractional distillation. (i) Which type of azeotrope is this? (ii) What type of deviation does it show? (iii) Why can it not be separated by fractional distillation? (5 marks)

Derive the relation between relative lowering of vapour pressure and molar mass of a non-volatile solute. Draw a graph comparing the vapour pressure curves of a solvent and a solution. (6 marks)

Explain the depression of freezing point with a labelled diagram. Derive the expression M2 = (1000 x Kf x w2)/(Delta Tf x w1). (6 marks)

Explain osmosis and osmotic pressure with a diagram. Show how osmotic pressure is used to determine molar mass, and explain why it is the best method for proteins and polymers. (6 marks)

Distinguish between ideal solutions and solutions showing positive and negative deviations from Raoult's law, with graphs, examples and the signs of Delta mix H and Delta mix V. (6 marks)

What is the van't Hoff factor? Explain abnormal molar masses due to association and dissociation, and write the modified expressions for all four colligative properties. (6 marks)