Benzene and toluene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fraction of benzene in vapour phase if 80 g of benzene is mixed with 100 g of toluene.

A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate:
(i) molar mass of the solute

How many mL of 0.1 M HCl are required to react completely with 1 g mixture of \(Na_{2}CO_{3}\) and \(NaHCO_{3}\) containing equimolar amounts of both?

Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol

A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate:
(ii) vapour pressure of water at 298 K.

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

Based on solute-solvent interactions, arrange the following in order of increasing solubility in n-octane and explain. Cyclohexane, KCl, \(CH_{3}OH\), \(CH_{3}CN\).

The depression in freezing point of water observed for the same amount of acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order given above. Explain briefly.

The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if the Henry’s law constants for oxygen and nitrogen at 298 K are \(3.30 \times 10^{7}\) mm and \(6.51 \times 10^{7}\) mm respectively, calculate the composition of these gases in water.

Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water?
(ii) toluene

Calculate the mass of a non-volatile solute (molar mass 40 g \(mol^{-1}\)) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Calculate the depression in the freezing point of water when 10 g of \(CH_{3}CH_{2}CHClCOOH\) is added to 250 g of water. \(K_{a} = 1.4 \times 10^{-3}\), \(K_{f} = 1.86\) K kg \(mol^{-1}\).

Gas	KH/k bar
Ar	40.3
CO2	1.67
HCHO	1.83 × 10−5
CH4	0.413

where K_H is Henry's Law constant in water. The order of their solubility in water is :

Define the following terms:
(ii) Molality

State Henry’s law and mention some important applications.

Determine the amount of \(CaCl_{2}\) (\(i\) = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 27° C.

Suggest the most important type of intermolecular attractive interaction in the following pairs.
(i) n-hexane and n-octane

A sample of drinking water was found to be severely contaminated with chloroform (\(CHCl_{3}\)) supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
(i) express this in percent by mass

Henry’s law constant for the molality of methane in benzene at 298 K is \(4.27 \times 10^{5}\) mm Hg. Calculate the solubility of methane in benzene at 298 K under 760 mm Hg.

Define the following terms:
(iii) Molarity