When 'x' × 10–2 mL methanol (molar mass = 32 g; density = 0.792 g/cm3) is added to 100 mL water (density = 1 g/cm3), the following diagram is obtained. Vapour pressure 270.65 273.15 Temperature/K x =…

Question

When 'x' × 10–2 mL methanol (molar mass = 32 g; density = 0.792 g/cm3) is added to 100 mL water (density = 1 g/cm3), the following diagram is obtained. Vapour pressure 270.65 273.15 Temperature/K x =………………(nearest integer) [Given: Molal freezing point depression constant of water at 273.15 K is 1.86 K kg mol–1]

Prashant Kotian · Accepted Answer

Correct answer: .. Tf = 273.15 – 270.65 = 2.5 K Tf = Kf m  2.5 = 1.86 × n 0.1  n = 0.1344 moles  w = 0.1344 × 32 = 4.3 g Volume = 4.3 0.792 = 5.43 ml = 543 × 10–2 ml

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