131.How many mL of 0.1 M HC1 are required to react completely with 1 g mixture of Na2CO3 and NaHCO3 containing equimolar amounts of both?
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132.A solution is obtained by mixing 300 g of 25% solution and 400 g of 40% solution by mass. Calculate the mass percentage of the resulting solution.
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133.An antifreeze solution is prepared from 222.6 g of ethylene glycol (C2H6O2) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL–1, then what shall be the molarity of the solution?
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134.A sample of drinking water was found to be severely contaminated with chloroform (CHCl3), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass): (i) express this in percent by mass (ii) determine the molality of chloroform in the water sample.
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Short Answer Type
135.The partial pressure of ethane over a solution containing 6.56 x 10–3 g of ethane is 1 bar. If the solution contains 5.00 x 10–2 g of ethane, then what shall be the partial pressure of th gas?
136.An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?
Consider 1 litre of solution, Osmotic pressure, π = 1.004 bar T = 273 K = 0.083 L atm K–1 mol–1 Volume of solution = 1 litre Weight of solute in 1 litre = 20 g Let the molar mas be Mb
Molar mass of non-volatile solute = 616.7 g mol–1.
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Long Answer Type
137.Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure, in bar of a mixture of 26.0 g of heptane and 35.0 g of octane?
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138.The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molar solution of a non-volatile solute in it.
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139.Calculate the mass of a non-volatile solute (molecular mass 40 g mol–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.
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Short Answer Type
140.If the density of some lake water is 1.25 g mL–1 and contains 92 g of Na+ ions per kg of water, calculate the molality of Na+ ions in the lake.