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Calculate the mass of ascorbic acid (Vitamin C, C_(6)H_(8)O_(6)) to be dissolved in 75 g g of acetic acid to lower its melting point by 1.5^(@)C, [K_(f)=3.9" K kg mol"^(-1)]. |
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Answer» Solution :Mass of ACETIC acid, `w_(1)=75 G` Molar mass of ascoric acid `(C_(6)H_(8)O_(6))`, `M_(2)=6xx12+8xx1+6xx16=176g mol^(-1)` Lowering of melting point, `Delta T_(f)=1.5 K` We know that : `K_(f)=3.9" K kg mol"^(-1)` `Delta T_(f)=(K_(f)XX w_(2)xx1000)/(M_(2)xx w_(1))` `w_(2)=(Delta t_(f)xx M_(2)xx w_(1))/(K_(f)xx1000)=(1.5xx176xx75)/(3.9xx1000)` = 5.08 gram = 5.08 g (approx) Hence, 5.08 g of ascorbic acid is needed to be dissolved. |
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