Urea forms an ideal solution in water. Determine the vapour press

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 Multiple Choice QuestionsShort Answer Type

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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]
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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)


Answer:

by using formula .

p° -pp° = xurea

let the mass of solution be 100g
therefore mass of urea = 10g
molecular mass of urea = 60 g

xurea = 10/60 = 1/6

molecular mass of water = 18 g
 xwater = 90/18 = 5

mole fraction of urea =xurea =1/61/6+5 = 1/631/6xurea =1/31using above formula 55.3-p55.3 =13155.3- p = 55.33155.3- 55.331 = p55.31-131 =pp= 55.3 ×3031 =53.52mm 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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