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221. A 0.1539 molal aqueous solution of cane sugar (mol. mass = 342 g mol^–1) has a freezing point of 271 K while the freezing point of pure water is 273.15 K. What will be the freezing point of an aqueous solution containing 5 g of gluocose (mol. mass = 180 g mol^–1) per 100 g of solution?

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222.

An aqueous solution of 2 percent non-volatile solute exerts a pressure of 0.096 atm at the boiling poine of the solvent. What is the molecular mass of the solute ?

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223. The vapour pressure of water is 12.3 kPa at 300 K. Calculate the vapour pressure of a one molal solution of a non-volatile, non-ionic solute in water.

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224. Why is the vapour pressure of a solution of glucose in water lower than that of water?

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225. A 6.90 M solution of KOH in water contains 30% by mass of KOH. Calculate the density of the KOH solution. [Molar mass of KOH = 56 g mol^–1]

Answer;

Let the density of solution = d g/cm³
and volume of solution is = 1L = 1000 cm³

mass of the solution = d xV
= (1000d)g

6.90 M solution mean 1L solution contains 6.90 moles of KOH
therefore mass of KOH = 6.90 x 56 = 386.4g

but only 30% of the solutionby mass is KOH
therefore

30/100 x (1000)d =386.4

and density is 1.288g/ cm³

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226. Give reasons for the following:
When 30 ml of ethyl alcohol and 30 ml of water are mixed, the volume of resulting solution is more than 60 ml.

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227. Give reasons for the following:
Copper is conducting as such while copper sulphate is conducting only in molten state or in aqueous solution.

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228. Urea forms an ideal solution in water. Determine the vapour pressure of an aqueous solution containing 10% by mass of urea at 40⁰C. (Vapour pressure of water at 40⁰C = 55.3 mm of Hg)

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229. Why is freezing point depression of 0.1 M sodium chloride solution nearly twice that of 0.1 M glucose solution?

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230. A 6.90 M solution of KOH in water contains 30% by mass of KOH. Calculate the density of the KOH solution. (Molar mass of KOH = 56 g mol^–1)

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225. A 6.90 M solution of KOH in water contains 30% by mass of KOH. Calculate the density of the KOH solution. [Molar mass of KOH = 56 g mol–1]

225. A 6.90 M solution of KOH in water contains 30% by mass of KOH. Calculate the density of the KOH solution. [Molar mass of KOH = 56 g mol^–1]