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What is the percent by mass of iodine needed to reduce the freezing point of benzene to `3.5^(@)"C"`? The freezing point and cryoscopic constant of pure benzene are `5.5^(@)"C"` and `5.12K/m` respectively. |
Answer» `Delta"T"_(f)="T"_(f)^(0)-"T"_(f)="K"_(f)."m"` `5.5^(@)"C"-3.5^(@)"C"=5012xxm` `m=2/5012=0.39" molal"` `therefore ` Mass of iodine needed for 1000g of benze`=mxx"molecular mass of iodine "I^(2)` `=0.39"mol//kgxx254g//mol=99.06g//kg` `therefore` 1000g+99.06g solution contain `99.06g "I"^(2)` 100g solution contains `99.06gxx100/1099.06g=9.01%` |
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